Glossary of Earthquake Terms

GLOSSERY TERMS SHORT (shortened list of the most important terms)

Term Definition
Acceleration

The rate of change of velocity of a
reference point. Commonly expressed as a fraction or percentage of the
acceleration due to gravity (g) where g = 980 cm/s2.

Active Fault A fault that is considered likely to
undergo renewed movement within a period of concern to humans. Faults
are commonly considered to be active if they have moved one or more
times in the last 10,000 years, but they may also be considered active
when assessing the hazard for some applications even if movement has
occurred in the last 500,000 years.
Aesthenosphere The highly viscous mechanically weak region
of the upper mantleof the Earth. It lies below the lithosphere, at
depths between 100 and 200 km below the surface, but perhaps extending
as deep as 400 km.
Aftershock Secondary tremors that may follow the
largest shock of an earthquake sequence. Such tremors can extend over a
period of weeks, months, or years.
Blind fault A fault that does not extend upward to the
Earth™s surface. It usually terminates upward in the axial region of an
anticline. If is dip is less than 45 degrees, it is a blind thrust.
Body Waves A seismic wave that propagates through the
interior of the Earth, as opposed to surface waves that propagate near
the Earth™s surface. P and S waves are examples. Each type of wave has
distinctive strain characteristics.
Building Code. A building code, or building control, is a
set of rules that specify the minimum acceptable level of safety for
constructed objects such as buildings and non-building structures. The
main purpose of building codes are to protect public health, safety and
general welfare as they relate to the construction and occupancy of
buildings and structures. A seismic code, refers to a building code
which uses earthquake-resistant design principles.
Continental Crust Outermost solid layer of the earth that
forms the continents and is composed of igneous, metamorphic, and
sedimentary rocks. Overall, the continental crust is broadly granitic in
composition. Contrast with oceanic crust.
Critical Structures 1)       Structures whose ongoing
performance during an emergency is required or whose failure could
threaten many lives. May include (1) structures such as nuclear power
reactors or large dams whose failure might be catastrophic; (2) major
communication, utility, and transportation systems; (3) involuntary- or
high-occupancy buildings such as schools or prisons; and (4) emergency
facilities such as hospitals, police and fire stations, and
disaster-response centers. , 2) The primary physical structures,
technical facilities and systems which are socially, economically or
operationally essential to the functioning of a society or community,
both in routine circumstances and in the extreme circumstances of an
emergency.2)       Critical Loss Facilities are hospital and health
care facilities, public buildings, telecommunications, airports, energy
systems (coal, nuclear etc.), bridges and other facilities that are
critical to the recovery and rehabilitation of a region post-earthquake.
Crust The outermost major layer of the Earth,
ranging from about 10 to 65 km in thickness worldwide. The continental
crust is about 40 km thick in the Pacific Northwest. The thickness of
the oceanic crust in this region varies between about 10 and 15 km.The
crust is characterized by P-wave velocities less than about 8 km/s. The
uppermost 15-35 km of crust is brittle enough to produce earthquakes.
The seismic crust is separated from the lower crust by the
brittle-ductile boundary.
Deep Earthquake An earthquake whose focus is located more
than 300 kilometers from the earth™s surface.

Earthquake-report.com differs from the official notification calling
earthquakes with a depth of more than 100 km as "Deep". This is mainly
because of the non-damaging impact of these earthquakes.

Depth The distance (usually measured in km) below
the surface of the earth delineated by 0km (the mean spheroid). Also
known as earthquake depth “ Earthquakes can occur anywhere between the
Earth™s surface and about 700 kilometers below the surface. For
scientific purposes, this earthquake depth range of 0 “ 700 km is
divided into three zones: shallow, intermediate, and deep.
Disaster An event that causes major disruption on
the economy, society and the environment.  Its origin or causes may be
directly derived from natural phenomena, i.e. geophysical (as volcanic
or seismic events that cause collapse of infrastructure, landslides or
liquefaction, etc.) or climatic (as hurricanes, typhoons, tornadoes,
major variation in rainfall both in terms of excess or deficit causing
drought). Although usually not covered by the methodology, disasters may
also have a œhuman or anthropic origin as chemical spills, industrial
accidents, or voluntarily caused events such as war, terrorist actions,
etc.  Disaster consequences or damage will always be associated with
human intervention before, during and after the event (the œdisaster
cycle).
Duration Time interval between the first and last
peaks of strong ground motion above a specified amplitude.
Earthquake Ground shaking and radiated seismic energy
caused most commonly by sudden slip on a fault, volcanic or magmatic
activity, or other sudden stress changes in the Earth. An earthquake of
magnitude 8 or larger is termed a great earthquake.
Earthquake Risk The expected (or probable) life loss,
injury, or building damage that will happen, given the probability that
some earthquake hazard occurs. Earthquake risk and earthquake hazard are
occasionally used interchangeably.
Epicenter The point on the Earth™s surface vertically
above the point (focus or hypocenter) in the crust where a seismic
rupture nucleates.
Fault Plane The surface on which the earthquake
movement takes place.
Fault Rupture See rupture front
Fault Scarp Steplike linear landform coincident with a
fault trace and caused by geologically recent slip on the fault.
Fault Trace Intersection of a fault with the ground
surface; also, the line commonly plotted on geologic maps to represent a
fault.
Faults A fracture along which there has been
significant displacement of the two sides relative to each other
parallel to the fracture.
Focal Depth A term that refers to the depth of an
earthquake focus.
Focus See hypocenter
Ground Motion (Shaking) General term referring to the qualitative
or quantitative aspects of movement of the Earth™s surface from
earthquakes or explosions. Ground motion is produced by waves that are
generated by sudden slip on a fault or sudden pressure at the explosive
source and travel through the Earth and along its surface.
Gutenberg-Richter Earthquakes appear to follow a pattern
through time in terms of no. of earthquakes vs. magnitude. This is
called the Gutenberg-Richter criterion.
Hazard Any physical phenomenon
associated with an earthquake that may produce adverse effects on human
activities. This includes surface faulting, ground shaking, landslides,
liquefaction, tectonic deformation, tsunami, and seiche and their
effects on land use, manmade structures, and socioeconomic systems. A
commonly used restricted definition of earthquake hazard is the
probability of occurrence of a specified level of ground shaking in a
specified period of time.
Hypocenter The point within the Earth where an
earthquake rupture initiates. Also commonly termed the focus.
Intensity A subjective numerical index describing the
severity of an earthquake in terms of its effects on the Earth™s surface
and on humans and their structures. Several scales exist, but the ones
most commonly used in the United States are the Modified Mercalli scale
and the Rossi-Forel scale.
Intermediate Earthquake An earthquake whose focus is located
between 70 to 300 kilometers from the earth™s surface.

Earthquake-report.com differs from the official notification calling
earthquakes with a depth of more than 40 to 00 km as "Intermediate".
This is mainly because of the limited damaging impact of these
earthquakes.

JMA The Japan Meteorological Agency seismic
intensity scale is a measure used in Japan and Taiwan to indicate the
strength of earthquakes. This scale is a numerical system, assigning
earthquakes levels 0-7.
Landslide An abrupt movement of geological materials
downhill in response to gravity. Landslides can be triggered by an
earthquake or other natural causes.
Latitude Angular distance north or south from the
earth™s equator measured through 90 degrees.
Liquefaction The transformation of a granular material
from a solid state into a liquefied state as a consequence of increased
pore water pressures and reduced effective stress. In engineering
seismology, it refers to the loss of soil strength as a result of an
increase in pore pressure due to ground motion. This effect can be
caused by earthquake shaking.
Lithosphere The outer solid part of the Earth,
including the crust and uppermost mantle. The lithosphere is about 100
km thick, although its thickness is age dependent.The lithosphere below
the crust is brittle enough at some locations to produce earthquakes by
faulting, such as within a subducted oceanic plate.
Local site conditions A qualitative or quantitative description
of the topography, geology, and soil profile at a site that affect
ground motions during an earthquake.
Locked Fault A fault that is not slipping because
frictional resistance on the fault is greater than the shear stress
across the fault. Such faults may store strain for extended periods that
is eventually released in an earthquake when frictional resistance is
overcome. A locked fault condition contrasts with fault-creep conditions
and an unlocked fault.
Logarithm It is simply the exponent required to
produce a given number. For a certain base 10, in this case 1 = 10, 2 =
10X10 = 100, 3=1000 and so on.
Longitude the arc or portion of the earth™s equator
intersected between the meridian of a given place and the prime meridian
and expressed either in degrees or in time.
Magnitude A number that characterizes the relative
size of an earthquake. Magnitude is based on measurement of the maximum
motion recorded by a seismograph(sometimes for earthquake waves of a
particular frequency),
corrected for attenuation to a standardized
distance. Several scales have been defined, but the most commonly used
are (1) local magnitude (ML), commonly referred to as œRichter
magnitude, (2) surface-wave magnitude (Ms), (3) body-wave
magnitude (Mb), and (4) moment magnitude (Mw). ML, Ms
and Mb have limited range and applicability and do not satisfactorily
measure the size of the largest earthquakes.

The moment magnitude (Mw) scale, based on the concept of seismic moment,
is uniformly applicable to all sizes of earthquakes but is more
difficult to compute than the other types. In principal, all magnitude
scales could be cross calibrated to yield the same value for any given
earthquake, but this expectation has proven to be only approximately
true, thus the need to specify the magnitude type as well as its value.An increase of one unit of magnitude (for example, from 4.6 to 5.6)
represents a 10-fold increase in wave amplitude on a seismogram or
approximately a 30-fold increase in the energy released. In other words,
a magnitude 6.7 earthquake releases over 900 times (30 times 30) the
energy of a 4.7 earthquake - or it takes about 900 magnitude 4.7
earthquakes to equal the energy released in a single 6.7 earthquake!
There is no beginning nor end to this scale. However, rock mechanics
seem to preclude earthquakes smaller than about -1 or larger than about
9.5. A magnitude -1.0 event releases about 900 times less energy than a
magnitude 1.0 quake. Except in special circumstances, earthquakes below
magnitude 2.5 are not generally not felt by humans.

Mainshock The biggest earthquake in a series is
termed the mainshock.
Mantle The layer of rock that lies between the
outer crust and the core of the earth. It is approximately 1,802 miles
(2,900 kilometers) thick and is the largest of the earth's major layers.
MMI The Mercalli scale rates the intensity of
shaking from an earthquake. The ratings vary from I (felt only under
especially favourable circumstances) to XII (total destruction).
Moment Magnitude See magnitude (Mw)
Ocean Spreading Ridge A fracture zone along the ocean bottom that
accommodates upwelling of mantle material to the surface, thus creating
new crust. This fracture is topographically marked by a line of ridges
that form as molten rock reaches the ocean bottom and solidifies.
Oceanic Crust The outermost solid layer of Earth that
underlies the oceans. Composed of the igneous rocks basalt and gabbro,
and therefore basaltic in composition. Contrast with continental crust.
Oceanic Trench A linear depression of the sea floor caused
by and approximately coincident with a subduction thrust fault.
Oscillator A mass that moves with oscillating motion
under the influence of external forces and one or more forces that
restore the mass to its stable at-rest position. In earthquake
engineering, an oscillator is an idealized damped mass-spring system
used as a model of the response of a structure to earthquake ground
motion. A seismograph is also an oscillator of this type
P Wave A seismic body wave that involves particle
motion (alternating compression and extension) in the direction of
propagation.
Peak Acceleration The highest acceleration in terms of value.
PGA The maximum acceleration amplitude measured
or expected in a strong-motion accelerogram of an earthquake.
Phase (1) A stage in periodic motion, such as
wave motion or the motion of an oscillator, measured with respect to a
given initial point and expressed in angular measure. (2) A pulse of
seismic energy arriving at a definite time.
Plate a large, relatively rigid segment of the
Earth™s lithosphere that moves in relation to other plates over the
asthenosphere.
Plate Tectonics A theory supported by a wide range of
evidence that considers the Earth™s crust and uppermantle to be composed
of several large, thin, relatively rigid plates that move relative to
one another. Slip on faults that define the plate boundaries commonly
results in earthquakes. Several styles of faults bound the plates,
including thrust faults along which plate material is subducted or
consumed in the mantle, oceanic spreading ridges along which new crustal
material is produced, and transform faults that accommodate horizontal
slip (strike slip) between adjoining plates.
Population Density Population density (in agriculture standing
stock and standing crop) is a measurement of population per unit area or
unit volume. It refers to people in our case.
Preparedness Definition: The knowledge and
capacities developed by governments, professional response and recovery
organizations, communities and individuals to effectively anticipate,
respond to, and recover from, the impacts of likely, imminent or current
hazard events or conditions.

Comment: Preparedness action is carried out within the context of
disaster risk management and aims to build the capacities needed to
efficiently manage all types of emergencies and achieve orderly
transitions from response through to sustained recovery. Preparedness is
based on a sound analysis of disaster risks and good linkages with early
warning systems, and includes such activities as contingency planning,
stockpiling of equipment and supplies, the development of arrangements
for coordination, evacuation and public information, and associated
training and field exercises. These must be supported by formal
institutional, legal and budgetary capacities. The related term
œreadiness describes the ability to quickly and appropriately respond
when required.

Prevention Actions or investments needed in the face
of imminent hazards. Distinct from mitigation, which is a permanent
strategy, prevention is seen as a pre-disaster set of activities.
Primary Wave See P Wave
Residential A building should be regarded as
residential building when more than half of the floor area is used for
dwelling purposes. Other buildings should be regarded as
non-residential.

Two types of residential buildings can be distinguished:

- houses (ground-oriented residential buildings):

comprising all types of houses (detached, semi-detached, terraced
houses, houses built in a row, etc.) each dwelling of which has its own
entrance directly from the ground surface;

- other residential buildings: comprising all residential buildings
other than ground-oriented residential buildings as defined above.

Resilience Definition: The ability of a system,
community or society exposed to hazards to resist, absorb, accommodate
to and recover from the effects of a hazard in a timely and efficient
manner, including through the preservation and restoration of its
essential basic structures and functions.Comment: Resilience means
the ability to œresile from or œspring back from a shock. The
resilience of a community in respect to potential hazard events is
determined by the degree to which the community has the necessary
resources and is capable of organizing itself both prior to and during
times of need.
Reverse Fault Dip-slip faults are inclined fractures
along which rock masses have mostly shifted vertically. If the rock
above the fault is elevated by slip, the fault is termed reverse (or
thrust fault).
Risk The probabilistic determination of the
damages a certain hazard can cause given the existing vulnerability,
location and time.
Risk Assessment Definition: A methodology to determine the
nature and extent of risk by analysing potential hazards and evaluating
existing conditions of vulnerability that together could potentially
harm exposed people, property, services, livelihoods and the environment
on which they depend.Comment: Risk assessments (and associated risk
mapping) include: a review of the technical characteristics of hazards
such as their location, intensity, frequency and probability; the
analysis of exposure and vulnerability including the physical social,
health, economic and environmental dimensions; and the evaluation of the
effectiveness of prevailing and alternative coping capacities in respect
to likely risk scenarios. This series of activities is sometimes known
as a risk analysis process.
Rupture The instantaneous boundary between the
slipping and locked parts of a fault during an earthquake. Rupture in
one direction on the fault is referred to as unilateral. Rupture may
radiate outward in a circular manner or it may radiate toward the two
ends of the fault from an interior point, referred to as bilateral.
S Wave Velocity The velocity of a secondary or S wave.
Generally measured in m/s.
Secondary Wave A seismic body wave that involves a
shearing motion in a direction perpendicular to the direction of
propagation. When it is resolved into two orthogonal components in the
plane perpendicular to the direction of propagation, SH denotes the
horizontal component and SV denotes the orthogonal component. Also known
as S waves and shear waves.
Seismic hazard Risk of a certain ground motion occurring
at a location (this can be defined by scenario modelling via stochastic
catalogues, DSHA, PSHA or other such methods, and can include different
types of earthquake effects)
Seismic Risk See earthquake risk, also the probabilistic
risk is the odds of an earthquake occurring and causing damage within a
given time interval and region.
Seismic Station A ground position at which a geophysical
instrument is located for an observation.
Seismic Waves An elastic wave generated by an impulse
such as an earthquake or an explosion. Seismic waves may propagate
either along or near the Earth™s surface (for example, Rayleigh and Love
waves) or through the Earth™s interior (P and S waves).
Seismicity 1)         The geographic and historical
distribution of earthquakes.

2)         A term introduced by Gutenberg and Richter to describe
quantitatively the space, time, and magnitude distribution of earthquake
occurrences. Seismicity within a specific source zone or region is
usually quantified in terms of a Gutenberg-Richter relationship.

Seismogram A record written by a seismograph in
response to ground motions produced by an earthquake, explosion, or
other ground-motion sources.
Seismometer A seismometer is a damped oscillating mass,
such as a damped mass-spring system, used to detect seismic-wave energy.
The motion of the mass is commonly transformed into an electrical
voltage. The electrical voltage is recorded on paper, magnetic tape, or
another recording medium. This record is proportional to the motion of
the seismometer mass relative to the Earth, but it can be mathematically
converted to a record of the absolute motion of the ground. Seismograph
is a term that refers to the seismometer and its recording device as a
single unit.
Sequence Pertains to the possible foreshock,
mainshock and aftershock occurrence and time period.
Severity Both intensity and magnitude “ i.e. the
size/strength of an earthquake.
Shakemaps ShakeMaps, a product of the United States
Geological Survey (USGS) Earthquake Hazards Program, are near-real-time
maps of ground motion and shaking intensity that are produced following
significant earthquakes. They appear as a set of links keyed to areas
which have recently experienced an earthquake. The maps display
instrumental intensity (modified Mercalli scale), peak ground
acceleration, and peak ground velocity. They are downloadable as image
(JPEG) or zipped postscript (PS) files, and datasets are downloadable as
text, zipped shapefiles, KML, XML, or HTML files. Older shakemaps are
stored in an archive. The most recent maps are also available as RSS
feeds.
Shallow Earthquake An earthquake whose focus is located within
70 kilometers of the earth™s surface.

Earthquake-report.com differs from the official notification calling
earthquakes with a depth up to 40 km as "Shallow". This is mainly
because of the possible damaging impact of these earthquakes.

Strike-Slip Strike-slip faults are vertical (or nearly
vertical) fractures along which rock masses have mostly shifted
horizontally. If the block opposite an observer looking across the fault
moves to the right, the slip style is termed right lateral; if the block
moves to the left, the motion is termed left lateral.
Subduction A plate tectonics term for the process
whereby the oceanic lithosphere collides with and descends beneath the
continental lithosphere.
Surface Faulting Displacement that reaches the Earth™s
surface during slip along a fault. Commonly accompanies moderate and
large earthquakes having focal depths less than 20 km. Surface faulting
also may accompany aseismic tectonic creep or natural or man-induced
subsidence.
Surface Wave Seismic waves that propagate along the
Earth™s surface. Love and Rayleigh waves are the most common.
Thrust fault A reverse fault in which the upper rocks
above the fault plane move up and over the lower rocks at an angle of 30o
or less so that older strata are placed over younger.
Tsunami An impulsively generated sea wave of local
or distant origin that results from large-scale seafloor displacements
associated with large earthquakes, major submarine slides, or exploding
volcanic islands.
Velocity In reference to earthquake shaking,
velocity is the time rate of change of ground displacement of a
reference point during the passage of earthquake seismic waves commonly
expressed in centimetres per second.

GLOSSERY TERMS COMPLETE (complete list of the most important terms)

Term Definition
˜Elements At Risk™ These are the elements of infrastructure that are
subjected to earthquake loading.
Acceleration

The rate of
change of velocity of a reference point. Commonly expressed as a
fraction or percentage of the acceleration due to gravity (g) where g =
980 cm/s2.

Accelerogram The record from an accelerograph showing ground
acceleration as a function of time.
Accelerograph A compact, rugged, and relatively inexpensive instrument
that records the signal from an accelerometer. Film is the most common
recording medium.
Accelerometer A sensor whose output is almost directly proportional to
ground acceleration. The conventional strong-motion accelerometer is a
simple, nearly critically damped oscillator having a natural
frequency of about 20 Hz “ 100Hz.
Acceptable Risk The level of potential losses that a society or
community considers acceptable given existing social, economic,
political, cultural, technical and environmental conditions for a
disaster.  In engineering terms, acceptable risk is also used to assess
and define the structural and non-structural measures that are needed in
order to reduce possible harm to people, property, services and systems
to a chosen tolerated level, according to codes or œaccepted practice
which are based on known probabilities of hazards and other factors.
Accuracy A measure of how close the results of an experiment are
to the true value; a measure of the correctness of the result.
Active Fault A fault that is considered likely to undergo renewed
movement within a period of concern to humans. Faults are commonly
considered to be active if they have moved one or more times in the last
10,000 years, but they may also be considered active when assessing the
hazard for some applications even if movement has occurred in the last
500,000 years.
Active tectonic regime A term that refers to regions where tectonic deformation
is relatively large and earthquakes are relatively frequent, usually
near plate boundaries.
Active tectonics The tectonic movements that are expected to occur or
that have occurred within a time span of concern to society.
Aesthenosphere The asthenosphere (from Greek asthenēs 'weak' +
sphere) is the highly viscous mechanically weak ductily-deforming region
of the upper mantleof the Earth. It lies below the lithosphere, at
depths between 100 and 200 km (~ 62 and 124 miles) below the surface,
but perhaps extending as deep as 400 km (~ 249 miles). It is involved in
plate movements and isostatic adjustments.
Affected Population Those affected in varying degree by a disaster.  They
should be specifically catalogued in terms of gender, social strata,
ethnic or other classification, including those belonging to physically
challenged, etc.  They are catalogued, in terms of severity of damage,
as:Primarily affected. Men, women, children of all social strata,
ethnic or social groups, whose livelihoods and welfare is severely
affected by a disaster in terms of deaths, injuries, losses or severe
damage to their houses and employment, and other major consequences on
their well being.  It includes also population evacuated, in temporary
shelters or that had to seek refuge after the event.

Secondarily affected. Men, women, children of all social strata,
ethnic or social groups that had indirect impact in their livelihoods in
welfare, that lived in the directly affected area (towns, communities,
area directly impacted by the disaster)

Tertiary. Men, women, children of all social strata, ethnic or social
groups that were impacted by overall (global economic and social)
effects by a disaster, i.e., increased prices in goods and services,
disruption in the provision of these, psychological trauma, etc.

Aftershock Secondary tremors that may follow the largest shock of
an earthquake sequence. Such tremors can extend over a period of weeks,
months, or years.
Age Of Building This is the amount of time from when the building was
constructed to the present time
Aid The act of assistance or supporting the vulnerable
population during a disaster.
Amplification An increase in seismic-signal amplitude within
some range of frequency as waves propagate through different earth
materials. The signal is both amplified and deamplified at the same site
in a manner that is dependent on the frequency band. The degree of
amplification is also a complex function of the level of shaking such
that, as the level of shaking increases, the amount of amplification may
decrease. Shaking levels at a site may also be increased by focusing of
seismic energy caused by the geometry of the sediment velocity
structure, such as basin subsurface topography, or by surface
topography.
Amplitude Zero-to-peak value of any wavelike disturbance “ i.e.
The maximum height of a wave crest of depth of a trough. (USGS
National Earthquake Information Center, 1999)
Analytical Using analysis via calculated or mathematical means.
Analytical Curves Curves (generally defining fragility of a building type)
derived by mathematical or first principles. i.e. mathematical-based
curves of damage for continuous ground motion intensities. These are
modelled rather than using historical data.
Analytical vulnerability method Vulnerability methods constructed via mathematical and
mechanical formulae to characterise the given damage per ground motion.
Annual Premium The annual premium is the amount of money you
will pay to have the insurance coverage against disasters.
Annual Probability of Exceedance The probability that a given level of seismic hazard
(typically some measure of ground motions, e.g., seismic magnitude or
intensity) or seismic risk (typically economic loss or casualties) can
be equalled or surpassed within an exposure time of one year.
Arias Intensity A ground-motion parameter derived from an accelerogram
and proportional to the integral over time of the acceleration squared.
Expressed in units of velocity (meters per second).
Aseismic Refering to a fault on which no earthquakes have been
observed. Aseismic may be due to lack of shear stress across the fault,
a locked-fault condition with or without shear stress, or release of
stress by fault creep.
Asperity A region on a fault of high strength produced by one or
more of the following conditions: increased normal stress, high
friction, low pore pressure, or geometric changes in the fault such as
fault bends, offsets, or roughness. This term is used in two contexts:
it may refer to sections of a fault that radiate uncommon seismic energy
or it may refer to locked sections of the fault that cause fault
segmentation.
Atc-13 In 1985 the Applied Technology Council (ATC) completed
and published the ATC-13 report, Earthquake Damage Evaluation Data
for California
.

Funded by the Federal Emergency Management Agency (FEMA), the ATC-13
report was developed to provide expert-opinion earthquake damage and
loss methodology and data for use in estimating local, regional, and
national economicimpacts from earthquakes in California

Attenuation A decrease in seismic-signal amplitude as waves
propagate from the seismic source. Attenuation is caused by geometric
spreading of seismic-wave energy and by the absorption and scattering of
seismic energy in different earth materials (termed anelastic
attenuation)
. Q and kappa are attenuation parameters used in the
attenuation of ground motions.
Attenuation Relation A mathematical expression that relates a ground-motion
parameter, such as the peak ground acceleration, to the source and
propagation path parameters of an earthquake such as the magnitude,
source-to-site distance, or fault type. Its coefficients are usually
derived from statistical analysis of earthquake records. It is a common
engineering term for a ground motion relation. Also see ground motion
prediction equation.
Basin Effects Where surface waves are trapped in basins or valleys,
and rebounding occurs causing increased or focussed ground motion
Bedrock Relatively hard, solid rock that commonly underlies
softer rock, sediment, or soil.
Blind fault A fault that does not extend upward to the Earth™s
surface. It usually terminates upward in the axial region of an
anticline. If is dip is less than 45 degrees, it is a blind thrust.
Body Waves A seismic wave that propagates through the interior of
the Earth, as opposed to surface waves that propagate near the Earth™s
surface. P and S waves are examples. Each type of wave has distinctive
strain characteristics.
Bottleneck A stage in a process that causes the entire process to
slow down or stop.
Brittle-Ductile Boundary A depth in the crust across which the thermomechanical
properties of the crust change from brittle above to ductile below. A
large percentage of the earthquakes in the crust initiate at or above
this depth on high-angle faults; below this depth, fault slip may be
aseismic and may grade from high angle to low angle.
Building Code. A building code, or building control, is a set of rules
that specify the minimum acceptable level of safety for constructed
objects such as buildings and non-building structures. The main purpose
of building codes are to protect public health, safety and general
welfare as they relate to the construction and occupancy of buildings
and structures. A seismic code, refers to a building code which uses
earthquake-resistant design principles.
Business Interruption Any event, whether anticipated (i.e., public service
strike) or unanticipated (i.e., blackout) which disrupts the normal
course of business operations at a location.
Capacity Spectrum method A method which looks at capacity of the structure in
terms of modelling the building as a simplified building versus the
hazard demand, and then finds the performance point to classify the
damage state.
Coherent Landslide Landslides that consist of a few relatively intact
blocks of rock or soil that move together. The basal failure surface of
most of these slides is several meters or tens of meters below the land
surface.
Collapse-Based A vulnerability method looking at the complex structural
dynamics of collapsed elements to construct an analytical vulnerability.
Commercial A building with 50% or more space that is dedicated to
offices.
Community A group of people either bounded through similar
location, sense of purpose, work or otherwise.
Community Capacity The combination of all the strengths, attributes and
resources available within a community, society or organization that can
be used to achieve agreed goals. Capacity may include infrastructure and
physical means, institutions, societal coping abilities, as well as
human knowledge, skills and collective attributes such as social
relationships, leadership and management. Capacity also may be described
as capability. Capacity assessment is a term for the process by which
the capacity of a group is reviewed against desired goals, and the
capacity gaps are identified for further action.
Community Structure This is the make up of the community (this is generally
classified based on economic, social, government, building and other
indicators).
Community Vulnerability See socio-economic vulnerability
Condition The quality of the infrastructure
Construction Material The type of material that a building or particular
infrastructure is made of.
Continental Crust Outermost solid layer of the earth that forms the
continents and is composed of igneous, metamorphic, and sedimentary
rocks. Overall, the continental crust is broadly granitic in
composition. Contrast with oceanic crust.
Continental Drift See plate tectonics
Coping Capacity The ability of people, organizations and systems, using
available skills and resources, to face and manage adverse conditions,
emergencies or disasters.
Cost-Benefit Cost/Benefit Analysis is a technique for deciding
whether to make a change. As its name suggests, it compares the values
of all benefits from the action under consideration and the costs
associated with it. The cost-benefit ratio is determined by dividing the
projected benefits of the programme by the projected costs. A programme
having a high benefit-cost ratio will take priority over others with
lower ratios.
Creep Slow, more or less continuous movement occurring on
faults due to ongoing tectonic deformation. Also applied to slow
movement of landslide masses down a slope because of gravitational
forces. Faults that undergo significant and (or) ongoing creep are
likely to be aseismic or capable of only small or moderate earthquakes.
This fault condition is commonly referred to as unlocked (see locked
fault and coupling).
Critical Structures 1)       Structures whose ongoing performance during an
emergency is required or whose failure could threaten many lives. May
include (1) structures such as nuclear power reactors or large dams
whose failure might be catastrophic; (2) major communication, utility,
and transportation systems; (3) involuntary- or high-occupancy buildings
such as schools or prisons; and (4) emergency facilities such as
hospitals, police and fire stations, and disaster-response centers. , 2)
The primary physical structures, technical facilities and systems which
are socially, economically or operationally essential to the functioning
of a society or community, both in routine circumstances and in the
extreme circumstances of an emergency.

2)       Critical Loss Facilities are hospital and health care
facilities, public buildings, telecommunications, airports, energy
systems (coal, nuclear etc.), bridges and other facilities that are
critical to the recovery and rehabilitation of a region post-earthquake.

Crust The outermost major layer of the Earth, ranging from
about 10 to 65 km in thickness worldwide. The continental crust is about
40 km thick in the Pacific Northwest. The thickness of the oceanic crust
in this region varies between about 10 and 15 km.The crust is
characterized by P-wave velocities less than about 8 km/s. The uppermost
15-35 km of crust is brittle enough to produce earthquakes. The seismic
crust is separated from the lower crust by the brittle-ductile boundary.
Damage Class Expected building damage ratios are calculated using
vulnerability methods, and are classified in number of limit/damage
states “ none, slight, partial, moderate, severe and collapse or
otherwise. It is essentially a range of percentages in terms of
infrastructure damage.
Damage Function Mathematical relationship for estimating building damage
due to ground shaking.
Damage Probability Matrices A matrix defining ratios of probable damage for each
building type for a given ground motion, or a vulnerability class.
Damage State Damage to building, transportation or lifeline systems
described in terms of the nature and extent of damage exhibited by its
components. Also see damage class.
Damage-Based Scale Like calculating the size of an earthquake, there are
also two main types of ground motion measurement “ damage-based.

Damage-based indices include MMI (Modified Mercalli Intensity) which
is a 12 class system ranging from no damage to complete destruction,
based on qualitative measurement of people™s perception of damage at a
location.

Other similar scales include MSK (Russia), JMA (Japan), EMS (Europe)
and Ross-Forel. They are not all with 12 damage levels.

Damage-Loss Conversion Damage Loss Conversion, can be defined as the mean
damage ratio (ratio of replacement & demolition to repair & restoration
cost (economically-speaking), or the social cost (i.e. number of
injuries, homeless and deaths).
Damping The reduction in amplitude of a seismic wave or
oscillator due to friction and (or) the internal absorption of energy by
matter.
Deep Earthquake An earthquake whose focus is located more than 300
kilometers from the earth™s surface.
Delinquency Rate The dollar amount of loans past due as a percentage of
the dollar amount of loans in a portfolio. The delinquency rate is
sometimes calculated on the basis of the number of loans delinquent
rather than the dollar amount of loans past due. The delinquency rate is
a measure of the proportion of a loan portfolio that is at risk.
Depth The distance (usually measured in km) below the surface
of the earth delineated by 0km (the mean spheroid). Also known as
earthquake depth “ Earthquakes can occur anywhere between the Earth™s
surface and about 700 kilometers below the surface. For scientific
purposes, this earthquake depth range of 0 “ 700 km is divided into
three zones: shallow, intermediate, and deep.
Design The engineering principles behind construction.
Design Earthquake The postulated earthquake (commonly including a
specification of the ground motion at a site)
that is used for
evaluating the earthquake resistance of a particular structure.
Design ground motion A level of ground motion used in structural design. It
is usually specified by one or more specific strong-motion parameters or
by one or more time series. The structure is designed to resist this
motion at a specified level of response, for example, within a given
ductility level.
Design Spectrum The specification of the required strength or capacity
of the structure plotted as a function of the natural period or
frequency of the structure and of the damping appropriate to earthquake
response at the required level. Design spectra are often composed of
straight-line segments and/or simple curves (e.g., as in most building
codes), but they can also be constructed from statistics of response
spectra of a suite of ground motions appropriate to the design
earthquake/s. To be implemented, the requirements of a design spectrum
are associated with allowable levels of stresses, ductilities,
displacements, or other measures of response.
Deterministic Seismic Hazard Assessment or DSHA Refers to methods of calculating ground motions for
single scenario earthquake (historical, maximum or user-defined) based
on earthquake-source models and wave- propagation methods that exclude
random effects.
Direct Economic Loss The costs of structural and non-structural repair,
damage to building contents, loss of building inventory, relocation
expenses, lost wages and lost income.
Direct Risk Negative consequences of disasters in terms of assets
lost, damaged or affected.  First perceived in physical terms, i.e.
miles of roads, hectares affected either in agricultural land, forests
or environmental reserves, production already completed but lost as tons
of agricultural products, numbers of industrial production units; or
infrastructure affected as number of health services™ facilities, number
of bed, schools or number or classrooms destroyed, etc.  Part of the
direct damage, although not quantified specifically in terms of monetary
value, are lives lost, injured persons and the primary, secondary or
tertiary affected population.
Directivity An effect of a propagating fault rupture whereby
earthquake ground motion in the direction of propagation is more severe
than that in other directions from the earthquake source.
Disaster An event that causes major disruption on the economy,
society and the environment.  Its origin or causes may be directly
derived from natural phenomena, i.e. geophysical (as volcanic or seismic
events that cause collapse of infrastructure, landslides or
liquefaction, etc.) or climatic (as hurricanes, typhoons, tornadoes,
major variation in rainfall both in terms of excess or deficit causing
drought). Although usually not covered by the methodology, disasters may
also have a œhuman or anthropic origin as chemical spills, industrial
accidents, or voluntarily caused events such as war, terrorist actions,
etc.  Disaster consequences or damage will always be associated with
human intervention before, during and after the event (the œdisaster
cycle).
Disaster Cycle The interconnected phases before, during and after the
occurrence of an event.  It links the prevention, early warning,
response, reconstruction and mitigation actions that are taken in the
face of an event.
Disaster Reduction The systemic approach to disasters that consists of
prevention and mitigation actions, investments, projects and strategies.
Disaster Risk The potential disaster losses, in lives, health status,
livelihoods, assets and services, which could occur to a particular
community or a society over some specified future time period.
Displacement The difference between the initial position of a
reference point and any later position. (1) In seismology, displacement
is the ground motion commonly inferred from a seismogram. For example,
it may be calculated by integrating an accelerogram twice with respect
to time and is expressed in units of length, such as meters. (2) In
geology, displacement is the permanent offset of a geologic or man-made
reference point along a fault or a landslide.
Displacement Capacity The capacity of the building measured in terms of
displacement. If the displacement capacity is exceeded, the building
will collapse.
Displacement-Based Pertaining to the use of displacement of a building to
calculate vulnerability i.e. the relationship of period of the ground
motion to displacement capacity (period of the building).
Disrupted Slide Landslides that are broken during movement into chaotic
masses of small blocks, rock fragments, or individual grains. The basal
failure surface of most such slides is within a few meters of the land
surface.
Ductility The property of a structure or a structural component
that allows it to continue to have significant strength after it has
yielded or begun to fail. Typically, a well-designed ductile structure
or component will show, up to a point, increasing strength as its
deflection increases beyond yielding, or cracking in the case of
reinforced concrete or masonry.
Duration Time interval between the first and last peaks of strong
ground motion above a specified amplitude.
Earthquake Ground shaking and radiated seismic energy caused most
commonly by sudden slip on a fault, volcanic or magmatic activity, or
other sudden stress changes in the Earth. An earthquake of magnitude 8
or larger is termed a great earthquake.
Earthquake catalogue A chronological listing of earthquakes. Early catalogues
were purely descriptive, giving the date of earthquakes and some
descriptions of its effects. Modern catalogues are usually quantitative,
listing a set of parameters describing the origin time, hypocenter
location, magnitude, moment tensor, etc.
Earthquake Record See seismogram
Earthquake Risk The expected (or probable) life loss, injury, or
building damage that will happen, given the probability that some
earthquake hazard occurs. Earthquake risk and earthquake hazard are
occasionally used interchangeably.
Economic Loss Conversion The conversion of damage to economic losses in dollar
amounts.
Elastic Rebound In seismology, a theoretical description of how an
elastic Earth responds to fault slip, as represented by a distribution
of displacement discontinuities.
Empirical Relating to the use of historic or measured data
Empirical Fatality Rate A rate of death, determined from past earthquake
records.
Empirical vulnerability method Vulnerability calculations constructed from historic
earthquake damage loss ratios and assessment.
EMS-98 European Macroseismic Scale “ another intensity measure
with scale 1-12, much the same as MMI
Epicentre The point on the Earth™s surface vertically above the
point (focus or hypocenter) in the crust where a seismic rupture
nucleates.
Essential Facilities Facilities that provide services and are key to the
functioning of a community are considered essential facilities. Examples
of essential facilities include hospitals, police stations, fire
stations, emergency operations centers (EOC), and schools. See also
critical facilities.
Evacuated People who are withdrawn from or vacated from a place or
area, especially as a protective measure.
Exposure Earthquake: Exposure is defined as the amount of human
activity located in the zones of seismic hazard as defined by the stock
of infrastructure in that location (usually defined by geocell).

Disaster: People, property, systems, or other elements present in
hazard zones that are thereby subject to potential losses. Measures of
exposure can include the number of people or types of assets in an area.
These can be combined with the specific vulnerability of the exposed
elements to any particular hazard to estimate the quantitative risks
associated with that hazard in the area of interest.

Fault Plane The surface on which the earthquake movement takes
place.
Fault Rupture See rupture front
Fault Scarp Steplike linear landform coincident with a fault trace
and caused by geologically recent slip on the fault.
Fault Trace Intersection of a fault with the ground surface; also,
the line commonly plotted on geologic maps to represent a fault.
Faults A fracture along which there has been significant
displacement of the two sides relative to each other parallel to the
fracture.
Field Survey A survey which is done by skilled personnel on-site
(usually of building damage or exposure/vulnerability data).
Filtering Attenuation of certain frequency components of a seismic
signal and the amplification of others. For a recorded signal, the
process can be accomplished electronically or numerically in a digital
computer. Filtering also occurs naturally as seismic energy passes
through the Earth.
Fire Following Earthquakes Any fire caused by the act of the earthquake or flow-on
effects of the earthquake.
First Motion On a seismogram, the direction of ground motion as the P
wave arrives at the seismometer. Upward ground motion indicates an
expansion in the source region; downward motion indicates a contraction.
Flexible Building A building that vibrates reasonably freely. This are
generally tall buildings, or long period structures.
Floodplain A land area adjacent to a river, stream, lake, estuary
or other water body that is subject to flooding.  These areas, if left
undisturbed, act to store excess floodwater.
Flow-On Effect An ongoing post-event effect that was influenced by the
direct earthquake effect.
Focal Depth A term that refers to the depth of an earthquake focus.
Focus See hypocentre
Focussing See amplification
Foreshock Foreshocks are relatively smaller earthquakes that
precede the biggest earthquake in a series, which is termed the
mainshock.
Fourier Amplitude Spectrum The relative amplitude at different component
frequencies that are derived from a time history by Fourier analysis.
Fragility For earthquakes, this refers to the vulnerability of the
building stock.
Fragility Function The function that describes the capacity of a building
for a certain hazard.
Frequency (building) The building frequency is a measure of the number of
times the building shakes back and forth every second. It is the
reciprocal of building period. If a building has a period of 2 seconds,
its frequency is 0.5 Hz (cycles per second).
Frequency (time) The rate at which something happens or is repeated.
Frequency (wave) the number of wave cycles per unit of time that pass a
given point. (usually measured in Hz)
Fundamental Period The longest period for which a structure shows a maximum
response. The reciprocal of natural frequency.
g A measure of acceleration where 1g = 9.81m/s2
Geocell A geographical area, used as a section of an analysis to
reflect a culmination of the aspects of that area.
Geologic Time Pertaining to a very long time in the history of the
Earth “ 1000s to 1000000s to 100000000s of years. The geologic time
scale provides a system of chronologic measurement relating stratigraphy
to time that is used by geologists, paleontologists and other earth
scientists to describe the timing and relationships between events that
have occurred during the history of the Earth.
Geometric Attenuation That component of attenuation of seismic-wave amplitudes
due to the radial spreading of seismic energy with distance from a given
source.
Geotechnical Refering to the use of scientific methods and
engineering principles to acquire, interpret, and apply knowledge of
earth materials for solving engineering problems.
GMPE or Ground Motion Prediction Equation Equations produced to predict the ground motion spectral
intensity at certain locations, given the site conditions, magnitude,
location and fault mechanism of a scenario earthquake, created using
earthquake ground motion record catalogues. This means that it is
possible to calculate the ground motion that could occur given a M7.0
earthquake on a fault 100km away, at this very location.

A Ground Motion Prediction Equation or GMPE is also known by the name
of attenuation relationship. They are generally of the following form:-
log[Sa(T)] = median fn(M,R,T,V) +
uncertainties,

where the logarithm of the median spectral acceleration (Sa) can be
calculated for given periods (T) using magnitudes (i.e. M=7.0),
distances (i.e. R=100km) and shear wave velocities (i.e. V=500m/s) at
this site.

The output is the median spectral acceleration and a standard
deviation of the uncertainties, as there are many uncertainties
associated with such a result.

Google Streetview Google Street View is a technology featured in Google
Maps and Google Earth that provides panoramic views from various
positions along many streets in the world.
Government Data Data that is maintained or collected by government
sources
Gross Domestic Product (GDP) The gross domestic product (GDP) or gross domestic
income (GDI) is a basic measure of a country™s overall economic output.
It is the market value of all final goods and services made within the
borders of a country in a year.
Ground Failure A general reference to landslides, liquefaction, and
lateral spreads.
Ground Motion (Shaking) General term referring to the qualitative or
quantitative aspects of movement of the Earth™s surface from earthquakes
or explosions. Ground motion is produced by waves that are generated by
sudden slip on a fault or sudden pressure at the explosive source and
travel through the Earth and along its surface.
Ground Shaking scenario A representation for a site or region depicting the
possible ground-shaking level or levels due to earthquake in terms of
useful descriptive parameters.
Gutenberg-Richter Earthquakes appear to follow a pattern through time in
terms of no. of earthquakes vs. magnitude. This is called the
Gutenberg-Richter criterion.
Hazard Any physical phenomenon associated with an
earthquake that may produce adverse effects on human activities. This
includes surface faulting, ground shaking, landslides, liquefaction,
tectonic deformation, tsunami, and seiche and their effects on land use,
manmade structures, and socioeconomic systems. A commonly used
restricted definition of earthquake hazard is the probability of
occurrence of a specified level of ground shaking in a specified period
of time.
Hazard Catalogue A catalogue of previous source, path and site for
details for previous earthquakes in a certain location.
Hazard Curve The relative hazard at a certain location for a certain
time period
Hazard Map A map of the relative hazard for a certain time period.
HAZUS Hazards United States (HAZUS) is a standardized
geographic information system (GIS) based loss estimation tool to
estimate potential losses from earthquakes, wind, and flood.
HDI The Human Development Index (HDI) is a composite
statistic used as an index to rank countries by level of œhuman
development and separate developed (high development), developing
(middle development), and underdeveloped (low development) countries.
The statistic is composed from statistics for Life Expectancy,
Education, and GDP collected at the national level.
Hertz (Hz) A unit of frequency. Expressed in cycles per second.
High-Risk An element where the risk is higher due to a population,
critical need or economic stress.
Historical Database A database containing data from past events
Homeless People needing immediate assistance for shelter.
Housing Financial or direct assistance from government to
individual. Occupants have their own lock and key. This type of housing
could include transient reimbursement, rental assistance, and direct
housing.
Hybrid Vulnerability Methods A combination of empirical and analytical methods to
calculate vulnerability.
Hypocentre The point within the Earth where an earthquake rupture
initiates. Also commonly termed the focus.
Indirect Risk Risk, either positive or negative, for flows related to
the production, provision, distribution or performance of goods and
services, i.e. additional costs of transport, reduced income of
enterprises, increased expenses of government, reduced tax revenues,
insurance payments received, increased imports or reduced exports, etc.
Indirect Economic Loss In addition to the direct physical damage and economic
losses, natural hazards like earthquakes cause a chain reaction, or
ripple effect, that is transmitted throughout the regional economy.
These could be business interruptions or disruption of retail
activities. Such interruptions are indirect economic losses due to an
event.
Industrial building A building with 50% or more space that is dedicated to
industrial activities.
Infrastructure The system of public works in a country, state or
region, including roads, utility lines and publicbuildings.
Injured People suffering from physical injuries, trauma or an
illness requiring medical treatment as a direct result of a disaster.
Insurance Insurance is defined as the equitable transfer of the
risk of a loss, from one entity to another, in exchange for a premium,
and can be thought of as a guaranteed and known small loss to prevent a
large, possibly devastating loss. An insurer is a company selling the
insurance; an insured or policyholder is the person or entity buying the
insurance. The insurance rate is a factor used to determine the amount
to be charged for a certain amount of insurance coverage, called the
premium.

Disaster: Government sponsored or private insurance policies for
protection against economic losses resulting from disaster.

Intensity A subjective numerical index describing the severity of
an earthquake in terms of its effects on the Earth™s surface and on
humans and their structures. Several scales exist, but the ones most
commonly used in the United States are the Modified Mercalli scale and
the Rossi-Forel scale.
Intermediate Earthquake An earthquake whose focus is located between 70 to 300
kilometers from the earth™s surface.
Interplate Interplate pertains to processes between the plates.
Interplate Coupling The qualitative ability of a subduction thrust fault to
lock and accumulate stress. Strong coupling implies that the fault is
locked and capable of accumulating stress, whereas weak coupling implies
that the fault is unlocked or only capable of accumulating low stress. A
fault with weak coupling could be aseismic or could slip by creep.
See Locked fault.
Intraplate Intraplate pertains to processes within the Earth™s
crustal plates.
Inventory (building) Collection of general building stock data that includes
residential, commercial, industrial, agricultural, religious,
government, and educational buildings.
Isoseismal Refering to a line on a map bounding points of equal
intensity for a particular earthquake.
JMA The Japan Meteorological Agency seismic intensity scale
is a measure used in Japan and Taiwan to indicate the strength of
earthquakes. This scale is a numerical system, assigning earthquakes
levels 0-7.
Kinematic Refering to the general movement patterns and directions
of the Earth™s rocks that produce rock deformation.
Landslide An abrupt movement of geological materials downhill in
response to gravity. Landslides can be triggered by an earthquake or
other natural causes.
Large Loss Facilities All sources of elements at risk which have high
population densities, such as sports stadiums, marketplaces, theatres,
churches/temples/mosques and schools. If an earthquake occurs at a
certain time, these losses will be huge.
Lateral Spreading Terms to landslides that commonly form on gentle slopes
and that have rapid fluid-like flow movement.
Latitude Angular distance north or south from the earth™s equator
measured through 90 degrees.
Lifelines Structures that are important or critical for urban
functionality. Examples are roadways, pipelines, powerlines, sewers,
communications, and port facilities.
Liquefaction The transformation of a granular material from a solid
state into a liquefied state as a consequence of increased pore water
pressures and reduced effective stress. In engineering seismology, it
refers to the loss of soil strength as a result of an increase in pore
pressure due to ground motion. This effect can be caused by earthquake
shaking.
Lithosphere The outer solid part of the Earth, including the crust
and uppermost mantle. The lithosphere is about 100 km thick, although
its thickness is age dependent.The lithosphere below the crust is
brittle enough at some locations to produce earthquakes by faulting,
such as within a subducted oceanic plate.
Local site conditions A qualitative or quantitative description of the
topography, geology, and soil profile at a site that affect ground
motions during an earthquake.
Locked Fault A fault that is not slipping because frictional
resistance on the fault is greater than the shear stress across the
fault. Such faults may store strain for extended periods that is
eventually released in an earthquake when frictional resistance is
overcome. A locked fault condition contrasts with fault-creep conditions
and an unlocked fault.
Logarithm It is simply the exponent required to produce a given
number. For a certain base 10, in this case 1 = 10, 2 = 10X10 = 100,
3=1000 and so on.
Longitude the arc or portion of the earth™s equator intersected
between the meridian of a given place and the prime meridian and
expressed either in degrees or in time.
Love Wave A type of seismic surface wave having a horizontal
motion that is transverse to the direction of propagation.
Ma. An abbreviation for one million years ago (Megannum).
Magnitude A number that characterizes the relative size of an
earthquake. Magnitude is based on measurement of the maximum motion
recorded by a seismograph(sometimes for earthquake waves of a
particular frequency),
corrected for attenuation to a standardized
distance. Several scales have been defined, but the most commonly used
are (1) local magnitude (ML), commonly referred to as œRichter
magnitude, (2) surface-wave magnitude (Ms), (3) body-wave magnitude
(Mb), and (4) moment magnitude (Mw). Scales 1-3 have limited range and
applicability and do not satisfactorily measure the size of the largest
earthquakes. The moment magnitude (Mw) scale, based on the concept of
seismic moment, is uniformly applicable to all sizes of earthquakes but
is more difficult to compute than the other types. In principal, all
magnitude scales could be cross calibrated to yield the same value for
any given earthquake, but this expectation has proven to be only
approximately true, thus the need to specify the magnitude type as well
as its value.

An increase of one unit of magnitude (for example, from 4.6 to 5.6)
represents a 10-fold increase in wave amplitude on a seismogram or
approximately a 30-fold increase in the energy released. In other words,
a magnitude 6.7 earthquake releases over 900 times (30 times 30) the
energy of a 4.7 earthquake - or it takes about 900 magnitude 4.7
earthquakes to equal the energy released in a single 6.7 earthquake!
There is no beginning nor end to this scale. However, rock mechanics
seem to preclude earthquakes smaller than about -1 or larger than about
9.5. A magnitude -1.0 event releases about 900 times less energy than a
magnitude 1.0 quake. Except in special circumstances, earthquakes below
magnitude 2.5 are not generally not felt by humans.

Magnitude-Frequency The relationship of size of earthquake to the number of
earthquakes in a given time.
Mainshock The biggest earthquake in a series is termed the
mainshock.
Mantle The layer of rock that lies between the outer crust and
the core of the earth. It is approximately 1,802 miles (2,900
kilometers) thick and is the largest of the earth's major layers.
Maximum probable earthquake (MCE) The maximum earthquake that could strike a given area
with a significant probability of occurrence.
Mean The average value, calculated by adding all the
observations and dividing by the number of observations.
Mean Damage Ratio, MDR The ratio of repair to replacement cost.
Median The median is the value halfway through the ordered data
set, below and above which there lies an equal number of data values. It
is generally a good descriptive measure of the location which works well
for skewed data, or data with outliers.
Mediation A problem-solving process in which an outside,
impartial, neutral party works with the element at risk to assist in
reaching a satisfactory solution to reduce disaster risk.
Microzonation The identification and mapping at local or site scales
of areas having different potentials for hazardous earthquake effects,
such as ground-shaking intensity, liquefaction, or landslide potential.
Microzonation for any of the earthquake hazards can be produced. ; The
division of a town or county into smaller areas according to their
variation in seismic hazard.
Mitigation Actions or investments needed to reduce risk, i.e.
exposure to hazards by reducing pre-existing vulnerability.
MMI The Mercalli scale rates the intensity of shaking from
an earthquake. The ratings vary from I (felt only under especially
favourable circumstances) to XII (total destruction).
Moho A discontinuity in seismic velocity that marks the
boundary between the Earth™s crust and mantle. Also termed the
Mohorovicic™ discontinuity, after the Croatian seismologist Andrija
Mohorovicic™ (1857-1936) who discovered it. The boundary is between 25
and 60 km deep beneath the continents and between 5 and 8 km deep
beneath the ocean floor.
Moment Magnitude See magnitude (Mw)
Mortality Rate Mortality rate is a measure of the number of deaths (in
general, or due to a specific cause) in some population, scaled to the
size of that population, per unit time. Mortality rate is typically
expressed in units of deaths per 1000 individuals per year; thus, a
mortality rate of 9.5 in a population of 100,000 would mean 950 deaths
per year in that entire population.
MSK The Medvedev-Sponheuer-Karnik scale, also known as the
MSK or MSK-64, is a macroseismic intensity scale used to evaluate the
severity of ground shaking on the basis of observed effects in an area
of the earthquake occurrence.
National Pertaining to a country level
Natural Frequency The discrete frequency(ies) at which a particular
elastic system vibrates when it is set in motion by a single impulse and
not influenced by other external forces or by damping. The reciprocal of
fundamental period.
Natural Logarithm The natural logarithm ln(x) is the logarithm to the base
˜e™, and mathematically the inverse function of the exponential function
ex. e is equal to approximately 2.7183
NEHRP Site Classes These are S-wave velocity in the top 30m of soil based
on classifications of soil type via the NEHRP (National Earthquake
Hazards Reduction Program). There are 5 classes of soil type from A
(hardest) to F (lowest). A is greater than 1500m/s, E is less than
180m/s in the top 30m and F are soils requiring site specific
evaluation. http://www.seis.utah.edu/urban/nehrp.shtml
Normal Dip-slip faults are inclined fractures along which rock
masses have mostly shifted vertically. If the rock mass above an
inclined fault is depressed by slip, the fault is termed normal.
Oblique Slip Oblique-slip faults have significant components of both
slip styles (strike and dip-slip)
Ocean Spreading Ridge A fracture zone along the ocean bottom that accommodates
upwelling of mantle material to the surface, thus creating new crust.
This fracture is topographically marked by a line of ridges that form as
molten rock reaches the ocean bottom and solidifies.
Oceanic Crust The outermost solid layer of Earth that underlies the
oceans. Composed of the igneous rocks basalt and gabbro, and therefore
basaltic in composition. Contrast with continental crust.
Oceanic Trench A linear depression of the sea floor caused by and
approximately coincident with a subduction thrust fault.
Oscillator A mass that moves with oscillating motion under the
influence of external forces and one or more forces that restore the
mass to its stable at-rest position. In earthquake engineering, an
oscillator is an idealized damped mass-spring system used as a model of
the response of a structure to earthquake ground motion. A seismograph
is also an oscillator of this type
P Wave A seismic body wave that involves particle motion
(alternating compression and extension) in the direction of propagation.
Path The direction that the wave energy travels along from
the source to the site.
Peak Acceleration The highest acceleration in terms of value.
Performance Point The intersection of building capacity and hazard
(demand) for a particular earthquake scenario
Period (Building) Measure of time that a building takes to shake back and
forth one time, as a response to an external force, e.g., earthquake
shaking. Tall buildings have longer periods on the order of 1 to 4
seconds. Short buildings move back and forth very rapidly and have
periods in the order of 0.1 to 0.4 seconds.
Period (Ground Motion) The time interval required for one full cycle of ground
motion movement (still a wave)
Period (Wave) The time interval between successive crests in a
sinusoidal wave train; the period is the inverse of the frequency of a
cyclic event.
Period Range That range of periods being considered in an analysis of
ground motion.
PGA The maximum acceleration amplitude measured or expected
in a strong-motion accelerogram of an earthquake.
Phase (1) A stage in periodic motion, such as wave motion or
the motion of an oscillator, measured with respect to a given initial
point and expressed in angular measure. (2) A pulse of seismic energy
arriving at a definite time.
Physical Vulnerability The vulnerability pertaining to infrastructure effects
from a disaster.
Plate a large, relatively rigid segment of the Earth™s
lithosphere that moves in relation to other plates over the
asthenosphere.
Plate Tectonics A theory supported by a wide range of evidence that
considers the Earth™s crust and uppermantle to be composed of several
large, thin, relatively rigid plates that move relative to one another.
Slip on faults that define the plate boundaries commonly results in
earthquakes. Several styles of faults bound the plates, including thrust
faults along which plate material is subducted or consumed in the
mantle, oceanic spreading ridges along which new crustal material is
produced, and transform faults that accommodate horizontal slip (strike
slip) between adjoining plates.
Poisson Distribution A probability distribution that characterizes discrete
events occurring independently of one another in time.
Policy The formal rules of the game “ including laws,
regulations and institutions. Policy reform may occur to address a
problem or achieve a goal such as improved earthquake resistant
building, changes in zonation for hazards.
Population Data Data on the people living in a certain area, including
age, detailed description of living conditions, employment and other
life-linked details.
Population Density Population density (in agriculture standing stock and
standing crop) is a measurement of population per unit area or unit
volume. It refers to people in our case.
Post-Event In the time occurring after the mainshock has finished.
Poverty Rate The state of being poor; lack of the means of providing
material needs or comforts.
Pre-Event Any time prior to the onset of the mainshock.
Preparedness Definition: The knowledge and capacities
developed by governments, professional response and recovery
organizations, communities and individuals to effectively anticipate,
respond to, and recover from, the impacts of likely, imminent or current
hazard events or conditions.

Comment: Preparedness action is carried out within the context
of disaster risk management and aims to build the capacities needed to
efficiently manage all types of emergencies and achieve orderly
transitions from response through to sustained recovery. Preparedness is
based on a sound analysis of disaster risks and good linkages with early
warning systems, and includes such activities as contingency planning,
stockpiling of equipment and supplies, the development of arrangements
for coordination, evacuation and public information, and associated
training and field exercises. These must be supported by formal
institutional, legal and budgetary capacities. The related term
œreadiness describes the ability to quickly and appropriately respond
when required.

Prevention Actions or investments needed in the face of imminent
hazards. Distinct from mitigation, which is a permanent strategy,
prevention is seen as a pre-disaster set of activities.
Primary Wave See P Wave
Probabilistic Seismic Hazard Assessment or PSHA Seismic hazard assessment using a probabilistic
combination of earthquake scenarios in order to determine the hazard for
the given area, generally to take into account the variability between
different earthquake scenarios.
Probability The number of cases that actually occur divided by the
total number of cases possible.
Probability of exceedance 1) The odds that the size of a future earthquake will
exceed some specified value.

2) The probability that, in a given area or site, an earthquake
ground motion will be greater than a given value during some time
period.

Probable Maximum Loss A probable upper limit of the losses that are expected
to occur as a result of a damaging earthquake, normally defined as the
largest monetary loss associated with one or more earthquakes proposed
to occur on specific faults or within specific source zones.
Rate An expression that describes a change in position or
velocity with respect to time.
Rate Of Exceedance How often a certain size earthquake will occur (usually
measured in no. of earthquakes per year) “ Rate of exceedance, is the
chance of the x-axis parameter is exceeded. Annual rate, refers to
1/return period. In the following diagram, there is a 0.0025% (0.000025)
chance in that year or one earthquake every 400000 years, a PGA of 0.43g
will be exceeded. There is a 0.001 (0.1%) chance that 0.1g will be
exceeded.
Rayleigh Wave A seismic surface wave causing an elliptical motion of a
particle at the free surface, with no transverse motion.
Recovery The restoration, and improvement where appropriate, of
facilities, livelihoods and living conditions of disaster-affected
communities, including efforts to reduce disaster risk factors.

The recovery task of rehabilitation and reconstruction begins soon
after the emergency phase has ended, and should be based on pre-existing
strategies and policies that facilitate clear institutional
responsibilities for recovery action and enable public participation.
Recovery programmes, coupled with the heightened public awareness and
engagement after a disaster, afford a valuable opportunity to develop
and implement disaster risk reduction measures and to apply the œbuild
back better principle.

Recurrence Interval The average time span between events (such as large
earthquakes, ground shaking exceeding a particular value, or
liquefaction) at a particular site. Also termed return period.
Reinsurance form of insurance that insurance companies buy for their
own protection, œa sharing of insurance. An insurer (the reinsured)
reduces its possible maximum loss on either an individual risk or a
large number of risks by giving (ceding) a portion of liability to
another insurance company (reinsurer).
Remote Sensing The science, technology and art of obtaining information
about objects or phenomena from a distance (i.e., without being in
physical contact with them). This is generally referring to the
collection of exposure data.
Repair Cost The cost of repairing the damage done to the property
(including demolition and debris removal if required).
Replacement Cost The cost of replacing property without a reduction for
depreciation. By this method of determining value, damages for a claim
would be the amount needed to replace the property using new materials.
Rescue Manpower The amount of human support for recovery and rescue,
post-disaster.
Reserves This is generally referring to the amount of assets that
are available when a disaster occurs.
Residential A building should be regarded as residential building
when more than half of the floor area is used for dwelling purposes.
Other buildings should be regarded as non-residential.

Two types of residential buildings can be distinguished:

- houses (ground-oriented residential buildings):

comprising all types of houses (detached, semi-detached, terraced
houses, houses built in a row, etc.) each dwelling of which has its own
entrance directly from the ground surface;

- other residential buildings: comprising all residential buildings
other than ground-oriented residential buildings as defined above.

Resilience Definition: The ability of a system, community or
society exposed to hazards to resist, absorb, accommodate to and recover
from the effects of a hazard in a timely and efficient manner, including
through the preservation and restoration of its essential basic
structures and functions.

Comment: Resilience means the ability to œresile from or œspring
back from a shock. The resilience of a community in respect to
potential hazard events is determined by the degree to which the
community has the necessary resources and is capable of organizing
itself both prior to and during times of need.

Resonance An increase in the amplitude of vibration in an elastic
body or system when the frequency of the shaking force is close to one
or more of the natural frequencies of a shaking body
Response The motion in a system resulting from shaking under
specified conditions.
Response Spectrum The maximum response to a specified acceleration time
series of a set of single-degree-of-freedom oscillators with chosen
levels of viscous damping, plotted as a function of the undamped natural
period or undamped natural frequency of the system. The response
spectrum is used for the prediction of the earthquake response of
buildings or other structures.
Retrofitting Definition: Reinforcement or upgrading of existing
structures to become more resistant and resilient to the damaging
effects of hazards,

Comment: Retrofitting requires consideration of the design and
function of the structure, the stresses that the structure may be
subject to from particular hazards or hazard scenarios, and the
practicality and costs of different retrofitting options. Examples of
retrofitting include adding bracing to stiffen walls, reinforcing
pillars, adding steel ties between walls and roofs, installing shutters
on windows, and improving the protection of important facilities and
equipment.

Return Period See recurrence interval.
Reverse Fault Dip-slip faults are inclined fractures along which rock
masses have mostly shifted vertically. If the rock above the fault is
elevated by slip, the fault is termed reverse (or thrust fault).
Risk The probabilistic determination of the damages a certain
hazard can cause given the existing vulnerability, location and time.
Risk Assessment Definition: A methodology to determine the nature and
extent of risk by analysing potential hazards and evaluating existing
conditions of vulnerability that together could potentially harm exposed
people, property, services, livelihoods and the environment on which
they depend.

Comment: Risk assessments (and associated risk mapping) include: a
review of the technical characteristics of hazards such as their
location, intensity, frequency and probability; the analysis of exposure
and vulnerability including the physical social, health, economic and
environmental dimensions; and the evaluation of the effectiveness of
prevailing and alternative coping capacities in respect to likely risk
scenarios. This series of activities is sometimes known as a risk
analysis process.

Rossi-Forel The Rossi-Forel scale is a measure of intensity of
shaking from an earthquake. This scale was replaced by the Mercalli
intensity scale.
Rupture The instantaneous boundary between the slipping and
locked parts of a fault during an earthquake. Rupture in one direction
on the fault is referred to as unilateral. Rupture may radiate outward
in a circular manner or it may radiate toward the two ends of the fault
from an interior point, referred to as bilateral.
Rupture Velocity The speed at which a rupture front propagates during an
earthquake.
S Wave Velocity The velocity of a secondary or S wave. Generally
measured in m/s.
Scenario A description of situations that could occur; it is a
set of informed assumptions about a situation
Screening Methods These methods involve assigning a vulnerability rating,
given different structural characteristics on an
infrastructure-by-infrastructure basis usually via site visit.
Secondary Wave A seismic body wave that involves a shearing motion in a
direction perpendicular to the direction of propagation. When it is
resolved into two orthogonal components in the plane perpendicular to
the direction of propagation, SH denotes the horizontal component and SV
denotes the orthogonal component. Also known as S waves and shear waves.
Sector Area of economic or social activity, such as
agriculture, industry, education, health services, etc.  Grouped, for
the purpose of valuation, into three: social, infrastructural and
productive (including both goods and services)
Seismic code See building code.
Seismic hazard Risk of a certain ground motion occurring at a location
(this can be defined by scenario modelling via stochastic catalogues,
DSHA, PSHA or other such methods, and can include different types of
earthquake effects)
Seismic Moment A measure of the size of an earthquake based on the area
of fault rupture, the average amount of slip, and the shear modulus of
the rocks offset by faulting. Seismic moment can also be calculated from
the amplitude spectra of seismic waves.
Seismic Risk See earthquake risk, also the probabilistic risk is the
odds of an earthquake occurring and causing damage within a given time
interval and region.
Seismic Risk Curve A plot of seismic risk (usually specified in terms of
annual probability of exceedance or return period) versus a specified
loss for a given property or portfolio of properties.
Seismic Station A ground position at which a geophysical instrument is
located for an observation.
Seismic Waves An elastic wave generated by an impulse such as an
earthquake or an explosion. Seismic waves may propagate either along or
near the Earth™s surface (for example, Rayleigh and Love waves) or
through the Earth™s interior (P and S waves).
Seismic Zonation Geographic delineation of areas having different
potentials for hazardous effects from future earthquakes. Seismic
zonation can be done at any scale “ national, regional, local, or site.
See Microzonation.
Seismic Zoning Map A map used to portray seismic hazard or seismic design
variables, for example, maps used in building codes to identify areas of
uniform seismic design requirements.
Seismicity 1)         The geographic and historical distribution of
earthquakes.

2)         A term introduced by Gutenberg and Richter to describe
quantitatively the space, time, and magnitude distribution of earthquake
occurrences. Seismicity within a specific source zone or region is
usually quantified in terms of a Gutenberg-Richter relationship.

Seismogram A record written by a seismograph in response to ground
motions produced by an earthquake, explosion, or other ground-motion
sources.
Seismometer A seismometer is a damped oscillating mass, such as a
damped mass-spring system, used to detect seismic-wave energy. The
motion of the mass is commonly transformed into an electrical voltage.
The electrical voltage is recorded on paper, magnetic tape, or another
recording medium. This record is proportional to the motion of the
seismometer mass relative to the Earth, but it can be mathematically
converted to a record of the absolute motion of the ground. Seismograph
is a term that refers to the seismometer and its recording device as a
single unit.
Sequence Pertains to the possible foreshock, mainshock and
aftershock occurrence and time period.
Severity Both intensity and magnitude “ i.e. the size/strength of
an earthquake.
Shakemaps ShakeMaps, a product of the United States Geological
Survey (USGS) Earthquake Hazards Program, are near-real-time maps of
ground motion and shaking intensity that are produced following
significant earthquakes. They appear as a set of links keyed to areas
which have recently experienced an earthquake. The maps display
instrumental intensity (modified Mercalli scale), peak ground
acceleration, and peak ground velocity. They are downloadable as image
(JPEG) or zipped postscript (PS) files, and datasets are downloadable as
text, zipped shapefiles, KML, XML, or HTML files. Older shakemaps are
stored in an archive. The most recent maps are also available as RSS
feeds.
Shallow Earthquake An earthquake whose focus is located within 70
kilometers of the earth™s surface.
Site The location where the earthquake ground motion is being
felt or measured
Site category The category of site geologic conditions affecting
earthquake ground motions based on descriptions of the geology,
measurements of the S-wave velocity standard penetration test, shear
strength, or other properties of the subsurface. For example, the site
geologic condition is classified into categories from A (hard rock) to F
(very soft soil), and different amplification factors are assigned for
them.
Site classification The process of assigning a site category to a site by
means of geologic properties (e.g., crystalline rock or Quaternary
deposits) or by means of a geotechnical characterization of the soil
profile (e.g., standard penetration test and S-wave velocity).
Site effect The effect of local geologic and topographic conditions
at a recording site on ground motions. It is implicitly assumed that the
source, path, and site effects on ground motions are separable.
Site response The modification of earthquake ground motion in the time
or frequency domain caused by local site conditions.
Slab Slab refers to any crustal plate that is consumed by the
Earth™s mantle. See Plate tectonics.
Slip The relative displacement of formerly adjacent points on
opposite sides of a fault, measured on the fault surface.
Slip Rate The average rate of displacement at a point along a
fault as determined from geodetic measurements, from offset man-made
structures, or from offset geologic features whose age can be estimated.
It is measured parallel to the predominant slip direction or estimated
from the vertical or horizontal separation of geologic markers.
Slum community The slum community was in turn defined as a geographical
entity where more than half of the households had the characteristics of
slum households. As data on security of tenure do not exist, the
estimates were based on the first four indicators, which were later
termed indicators of shelterdeprivation. To avoid introducing too many
concepts simultaneously, the terms œshelter deprivation and œslums are
used to reflect the same phenomenon.
Slum household The proportion of slum dwellers within the urban
population refers to the number of households; the slum household,
therefore, was defined as an entity which lacked one or more of the
following conditions:

(a) Access to improved water supply;

(b) Access to improved sanitation;

(c) Durability of housing;

(d) Adequate living space;

(e) Security of tenure.

Social Disparity Index An index design to show the differences in social
settings between two entities.
Social Loss Conversion The conversion of building damage to social loss
estimates (deaths, injured, homeless, affected etc.)
Socio-Economic Vulnerability The susceptibility of short and medium-term conditions
for (a) key economic indicators and overall economic performance and (b)
key social indicators and social capital “ it is essentially any
vulnerability not pertaining directly to infrastructure (physical
vulnerability), which has an aggravating effect. It can also be classed
as the vulnerability of the community. i.e. the people and economics at
risk.
Soil All unconsolidated material above the bedrock
Soil amplification Growth in the amplitude of earthquakes when seismic
waves pass from rock into less rigid material such as soil.
Source The geologic structure that generates a particular
earthquake.
Spectral Acceleration 1)       This is the acceleration measured at different
periods at a seismic station. Commonly refers to either the Fourier
amplitude spectrum of ground acceleration or the PSRV.

2)       Response of a suite of single-degree-of-freedom oscillators
to an earthquake, used to represent forces on a structure. (The
acceleration of earthquake motion at a specified building period)

Spectral Amplification A measure of the relative shaking response of different
geologic materials. The ratio of the Fourier amplitude spectrum of a
seismogram recorded on one material to that computed from a seismogram
recorded on another material for the same earthquake or explosion.
Spectrum In seismology, a curve showing amplitude and phase as a
function of frequency or period.
Standard Deviation The square root of the average of the squares of
deviations about the mean of a set of data. Standard deviation is a
statistical measure of spread or variability.
Stiff Buildings A building that does not vibrate very freely
Stochastic Applied to processes that have random characteristics.
Stress Force per unit area acting on a plane within a body. Six
values are required to characterize completely the stress at a point:
three normal components and three shear components.
Strike-Slip Strike-slip faults are vertical (or nearly vertical)
fractures along which rock masses have mostly shifted horizontally. If
the block opposite an observer looking across the fault moves to the
right, the slip style is termed right lateral; if the block moves to the
left, the motion is termed left lateral.
Strong Motion Ground motion of sufficient amplitude and duration to be
potentially damaging to a building™s structural components or
architectural features.
Subduction A plate tectonics term for the process whereby the
oceanic lithosphere collides with and descends beneath the continental
lithosphere.
Surface Faulting Displacement that reaches the Earth™s surface during
slip along a fault. Commonly accompanies moderate and large earthquakes
having focal depths less than 20 km. Surface faulting also may accompany
aseismic tectonic creep or natural or man-induced subsidence.
Surface Wave Seismic waves that propagate along the Earth™s surface.
Love and Rayleigh waves are the most common.
Tectonic Region Tectonic refers to rock-deforming processes and
resulting structures that occur over regional sections of the
lithosphere. Thus, the tectonic region is generally defined as the
location which is either active, stable, subductive, volcanic etc.
Telecommunications transmission of signals over a distance for the purpose
of communication “ internet, telephone etc.
Thrust fault A reverse fault in which the upper rocks above the fault
plane move up and over the lower rocks at an angle of 30o or
less so that older strata are placed over younger.
Time History The sequence of values of any time “ varying quantity
(such as a ground motion measurement)
measured at a set of fixed
times. Also termed time series.
Topography The relief features or surface configuration of an area.
Transportation In this course, pertaining to a method of transport
Traveltime Curve A graph of arrival times, commonly P or S waves,
recorded at different points as a function of distance from the seismic
source. Seismic velocities within the Earth can be computed from the
slopes of the resulting curves.
Tsunami An impulsively generated sea wave of local or distant
origin that results from large-scale seafloor displacements associated
with large earthquakes, major submarine slides, or exploding volcanic
islands.
Tsunamigenic Refering to those earthquake sources, commonly along
major subduction-zone plate boundaries such as those bordering the
Pacific Ocean, that can generate tsunamis.
Uncertainty error; an estimate of the differences in values from
test to test that are divided into two types, systematic and random,
depending on their origin.
Unconsolidated Loosely arranged, not cemented together, so particles
separate easily.
Variability The range of possible outcomes of a given situation.
Velocity In reference to earthquake shaking, velocity is the time
rate of change of ground displacement of a reference point during the
passage of earthquake seismic waves commonly expressed in centimetres
per second.
Vulnerability 1) Conditions of economic, physical, social and
environmental infrastructure that determine the probability that a
certain hazard will cause a certain degree of damage. 2) This can also
be defined as susceptibility of the infrastructure stock. 3) The
characteristics and circumstances of a community, system or asset that
make it susceptible to the damaging effects of a hazard.
Vulnerability Analysis Vulnerability analysis is the process of estimating the
vulnerability to potential disaster hazards of specified elements at
risk
Vulnerability Curves A curve showing the relative vulnerability of a building
or infrastructure element given a certain hazard.
Vulnerability Indices An index showing the relative vulnerability of a
building or infrastructure element given a certain hazard.
Warning System Arrangements to rapidly disseminate information
concerning imminent disaster threats to government officials,
institutions and the population at large in the areas at immediate risk.
They normally relate to tropical storms and floods.
Wavefront Imaginary surface or line that joins points at which the
waves from a source are in phase (e.g., all at a maximum or all at a
minimum).
Wavelength The distance between successive points of equal
amplitude and phase on a wave (for example, crest to crest or
trough to trough)
.
Zoning Zoning is the process in physical planning, or the
results thereof, in which specific functions or uses are assigned to
certain areas (for example, industrial zones, residential areas)


http://www.cedim.de - CEDIM
http://rev.seis.sc.edu/definition.html - REV
http://www.treasurers.org/glossary - ACT
http://www.stats.gla.ac.uk/steps/glossary/presenting_data.html#med “ STEPS
OECD Glossary of Terms - OECD
Relief Web Glossary of Terms “ Relief Web
USGS Glossary of Terms - http://earthquake.usgs.gov/learn/glossary/ - USGS
Prevention Web Glossary of Terms “ Prevention Web
Earthquake Canada Glossary of Terms “ EQ Canada
International Red Cross. - ICRC
http://www.icwgroup.com/earthquake/earthquake-glossary.html
- ICW Group
http://www.quake.utah.edu/REGIONAL/gloss.htm -Earthquake glossary - UTAH
http://www4.uwm.edu/letsci/geosciences/seismic_center/seis_dictionary.cfm
-
U Milwaukee

http://www.pdc.org/iweb/earthquake_terms.jsp
- PDC http://www.hazus.org/DATA_STANDARDIZATION/HAZUS99_Data_Standardization_Guidelines.pdf