Moderate shallow quake in Central California + “I Have Felt It reports”

Last update: August 30, 2011 at 2:11 pm by By

Earthquake overview : A moderate but very shallow and thus moderately dangerous earthquake rattled through Central California just after midnight. Luckily in a scarcely populated area.

We ask people who have felt this earthquake to share their information with our many readers (also from your area). Please use the “I Have Felt it” form below.

UPDATE 30/08 – 06:53 LT :  Another weak aftershock measuring 2.6 at 7 km (4 miles) NW (326°) from Pinnacles, CA and 24 km (15 miles) ENE (70°) from Gonzales, CA. the earth keeps moving.
The pattern of the many small quakes at various locations along the San Andreas fault has to be noticed. This morning weak 2.9 M earthquake almost below San Fransisco was another sign of the activity of the fault.

UPDATE 28/08 – 18:13 UTC : Aftershocks on August 28 UTC :
M 3.0      2011/08/28 17:04 Depth 6.9 km
M 2.7      2011/08/28 12:17 Depth 7.6 km
M 3.0      2011/08/28 03:03 Depth 5.6 km

UPDATE 10:00 UTC : Since the mainshock of 4.8, we have recorded 5 aftershocks measuring :  3.6, 2.6, 3.3, 2.7 and 2.5. Epicenters in

UPDATE : We can only notice an increase in activity along the Central California San Andreas fault (red line on map) and this in 2 locations with multiple earthquakes. Let us hope it stops here.

 

Detail of earthquakes on August 26 and 27 along the San Andreas fault. The biggest dots are +4, the smallest +1

UPDATE : the Pine Rock Fault Zone is very close to the greater San Andreas fault line

Landscape in the greater earthquake epicenter area - Panoramio image courtesy Carolyn - http://www.panoramio.com/photo/32600462

UPDATE : In a radius of 10 miles around the current epicenter, we notices 5 other earthquakes.
M 3.1, August 15, 2011 08:20:27 UTC Depth: 4.07 km (2.53 mi)
M 3.1, July 3, 2011 18:56:55 UTC Depth:    11.30 km (7.02 mi)
M 3.0, July 6, 2011 07:19:58 UTC Depth:    7.05 km (4.38 mi)
M 3.8, July 6, 2011 07:18:52 UTC Depth:    7.59 km (4.72 mi)
M 3.1, June 14, 2011 19:05:28 UTC Depth: 6.10 km (3.79 mi)

UPDATE : The location of occurrence is right on the San Adreas Fault and close to the Pine Rock Fault zone, responsible for a number of moderate quakes since the beginning of June 2011.

UPDATE : The earthquake has been felt as far as San Fransisco, Fresno and Templeton

UPDATE : the epicenter is very close to Pinnacles National Monument. The Monument’s namesakes are the eroded leftovers of half of an extinct volcano.

UPDATE : The area has been hit by several shocks the last couple of weeks, this is however the strongest since the sequence started.

UPDATE : Luckily, the direct epicenter area is very scarcely populated and is at least 20 km from the farming Gonzales valley.

UPDATE : The earthquake occurred very close to road 25 which links San Benito to Ridgemark.

UPDATE : Maximum calculated MMI is V (moderate shaking). It will be experienced by 57 people , a IV MMI by nearly 35,000 people. A weak III MMI shaking by nearly a million people

UPDATE : The earthquake was first reported as a 4.8 earthquake.

“I Have Felt It” reports as received by Earthquake-Report.com
MMI values (if indicated) after the text (III: Weak shaking, IV Light shaking, V Moderate shaking, VI Strong shaking, VII Very Strong shaking)
Carmel Valley, CA – Weak shaking MMI III
95005, CA – Light shaking indicated – MMI IV
Salinas, CA – Dizzy – III
Carmel Valley, CA – Shook the house strongly enough to creaking and wake me from sleep.  Lasted about 10 seconds.  No pictures moved or things broken.  Too late to check the foundation, but no obvious inside damage. – V MMI
Santa Cruz, CA – Just enough to wake me up – III
Santa Cruz, CA – Light shaking indicated – MMI IV
Carmel Valley, CA – Shook the house strongly enough to creaking and wake me from sleep.  Lasted about 10 seconds.  No pictures moved or things broken.  Too late to check the foundation, but no obvious inside damage. – V
Carmel Valley, CA – III indicated (weak shaking).
Monterey, Forest Ridge Rd, 93940 – Sitting on the couch watching tv and the couch started shaking and jumping. Probably only for about 5-10secs. We live on a slope though, with half of our apartment supported by 20ft columns — so this probably increased the magnitude of our experience. – MMI V
Monterey, CA – Was lying in bed when the bed started shaking for about 8 seconds, no audible noise from surroundings. – MMI IV
Santa Cruz, CA – Very mild and short – MMI III
Kings Canyon National Park - Bed was shaking in our cabin in kings canyon national park around midnight of the 25th turning to the 26th. – MMI IV

Most important Earthquake Data:
Magnitude : 4.6
UTC Time : Saturday, August 27, 2011 at 07:18:21 UTC
Local time at epicenter : Saturday, August 27, 2011 at 12:18:21 AM at epicenter
Depth (Hypocenter) : 7.6 km
Geo-location(s) :
7 km (4 miles) NNW (330°) from Pinnacles, CA
21 km (13 miles) NE (38°) from Soledad, CA
35 km (22 miles) SE (146°) from Hollister, CA
105 km (65 miles) SE (143°) from San Jose City Hall, CA

Links to important maps
USGS Did You Feel It Map
Google satellite map of the area showing the kind of terrain the earthquake took place
USGS Human impact map
USGS historic earthquakes map
USGS Seismic hazard map

QuakeSOS+ and QuakeSOS free are iPhone applications developed by Armand Vervaeck, the founder of Earthquake Report. The Application simplifies immediate group communication to friends and family members (with your exact GPS location) and is feeding the users with Earthquake Report news. The 0.99 US$ QuakeSOS+ version will support the activities of SOS Earthquakes.

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I did feel it – Ik heb het gevoeld – Το έκανα αισθάνεται – Yo lo siento – 我的确感到了 – 私はそれを感じていました- Ich habe es gefühlt – Bunu hissediyorum yaptı – لم أشعر أنه

Country and location
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Tell us where in which location you felt the earthquake
E-mail (only if you wish)
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Your Email address might help us if we request for additional details about your experience. This field is NOT mandatory. It is up to you to give it or not.
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People :
Felt by persons at rest, on upper floors or favorably placed.
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People :
Felt indoors; hanging objects may swing, vibration similar to passing of light trucks, duration may be estimated, may not be recognized as an earthquake.
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People :
Generally noticed indoors but not outside. Light sleepers may be awakened. Vibration may be likened to the passing of heavy traffic, or to the jolt of a heavy object falling or striking the building.
Fittings :
Doors and windows rattle. Glassware and crockery rattle. Liquids in open vessels may be slightly disturbed. Standing motorcars may rock.
Structures :
Walls and frames of buildings, and partitions and suspended ceilings in commercial buildings, may be heard to creak.
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People :
Generally felt outside, and by almost everyone indoors. Most sleepers awakened. A few people alarmed.
Fittings :
Small unstable objects are displaced or upset. Some glassware and crockery may be broken. Hanging pictures knock against the wall. Open doors may swing. Cupboard doors secured by magnetic catches may open. Pendulum clocks stop, start, or change rate.
Structures :
Some large display windows cracked. A few earthenware toilet fixtures cracked.
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People Felt by all. People and animals alarmed. Many run outside. Difficulty experienced in walking steadily.
Fittings :
Objects fall from shelves. Pictures fall from walls. Some furniture moved on smooth floors, some unsecured free-standing fireplaces moved. Glassware and crockery broken. Very unstable furniture overturned. Small church and school bells ring. Appliances move on bench or table tops. Filing cabinets or "easy glide" drawers may open (or shut).
Structures :
Slight damage to buildings with low standard. Some stucco or cement plaster falls. Large display windows broken. Damage to a few weak domestic chimneys, some may fall.
Environment :
Trees and bushes shake, or are heard to rustle. Loose material may be dislodged from sloping ground, e.g. existing slides, talus slopes, shingle slides.
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People
General alarm. Difficulty experienced in standing. Noticed by motorcar drivers who may stop.
Fittings :
Large bells ring. Furniture moves on smooth floors, may move on carpeted floors. Substantial damage to fragile contents of buildings.
Structures :
Unreinforced stone and brick walls cracked. Low standard buildings cracked with some minor masonry falls. A few instances of damage to buildings of ordinary workmanship. Unbraced parapets, unbraced brick gables, and architectural ornaments fall. Roofing tiles, especially ridge tiles may be dislodged. Many unreinforced domestic chimneys damaged, often falling from roof-line. Water tanks Type I burst. A few instances of damage to brick veneers and plaster or cement-based linings. Unrestrained water cylinders (hot-water cylinders) may move and leak. Some common windows cracked. Suspended ceilings damaged.
Environment :
Water made turbid by stirred up mud. Small slides such as falls of sand and gravel banks, and small rock-falls from steep slopes and cuttings. Instances of settlement of unconsolidated or wet, or weak soils. Some fine cracks appear in sloping ground. A few instances of liquefaction (i.e. small water and sand ejections).
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People Alarm may approach panic. Steering of motorcars greatly affected. Structures : Low standard buildings heavily damaged, some collapse. ordinary workmanship buildings damaged, some with partial collapse. Reinforced masonry or concrete buildings damaged in some cases. A few instances of damage to buildings and bridges designed and built to resist earthquakes. Monuments and pre-1976 elevated tanks and factory stacks twisted or brought down. Some pre-1965 infill masonry panels damaged. A few post-1980 brick veneers damaged. Decayed timber piles of houses damaged. Houses not secured to foundations may move. Most unreinforced domestic chimneys damaged, some below roof-line, many brought down. Environment : Cracks appear on steep slopes and in wet ground. Small to moderate slides in roadside cuttings and unsupported excavations. Small water and sand ejections and localized lateral spreading adjacent to streams, canals, lakes, etc.
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Structures Many low standard buildings destroyed. Ordinary workmanship buildings heavily damaged, some collapse. Reinforced masonry or concrete buildings damaged, some with partial collapse. Buildings and bridges designed and built to resist earthquakes damaged in some cases, some with flexible frames seriously damaged. Damage or permanent distortion to some buildings and bridges, designed and built to normal use standards. Houses not secured to foundations shifted off. Brick veneers fall and expose frames. Environment : Cracking of ground conspicuous. Landsliding general on steep slopes. Liquefaction effects intensified and more widespread, with large lateral spreading and flow sliding adjacent to streams, canals, lakes, etc.
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Comments

  1. Susan says:
    August 28, 2011 at 8:49 pm

    Thanks for posting these earthquakes and keeping us posted. I really appreciate all you do.

    Reply

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