Strong earthquake near Sao Miguel (and Santa Maria Island), Azores Islands, Portugal

Update 10:18 UTC : João Luís Gaspar the executive director of the Center for Monitoring and Information Sismovulcânica Azores (CIVISA) said :  "This is an earthquake of tectonic origin, very  normal for this area of ​​the archipelago . The Magnitude was relatively high. The mainshock has been followed by a few aftershocks, two of which are felt on the island of São Miguel with low intensity".

Update 09:28 UTC : The location of this earthquake is keeping us focused on this earthquake. A question : was this a volcanic earthquake ? Scientists will certainly look into this. The location of the epicenter is following the data of the Azores Seismological center right on the spreading ridge. The Google Earth map below this text is showing the spreading ridge (ripple on the map) activity and the submarine volcanoes surrounding the ridge.  The top of the highest volcano is however still 1800 meter below sea level. The depth of the ridge area itself 2500 to 3000 meter. It would be very interesting at this moment to have a ROV (Remote Vehicle) searching the epicenter area, however this is of course a dream as the use of these very expensive tools are planned a long time ahead.

Screen Shot 2013-04-30 at 11.25.29

Update 09:08 UTC :
- A lot of people on Sao Miguel were frightened by the quake and ran into the streets.
- Firefighter departments have however not received any reports of damage so far.
- The image below is the location of the epicenter as reported by USGS (an error margin of 10 to 15 km is part of seismology - the precise location will be determined later).
- The red line is the fault line. The quake happened almost within the fault line. The fault is a zig zag diverging plate fault or spreading tectonic plates. Spreading plates are also the reason for the volcanism on the Azores. Why earthquakes on spreading plates ? As the fault is not a straight line but in this place a zigzag line, plates can hang on such a location until the stress gets too high and breaks. This happened today.

Screen Shot 2013-04-30 at 11.01.36

Update 07:56 UTC : The graphic below shows the aftershocks which have been reported so far (4 in total)

Screen Shot 2013-04-30 at 09.55.16

Update 07:50 UTC : Statement from the seismological agency of the Azores : Strong earthquake felt with maximum intensity V-VI in S. Miguel.  The Monitoring and Information Centre Sismovulcânica Azores (CIVISA) reports  an earthquake with magnitude 5.9 (Richter) and its epicenter about 34 km SE of the island of S. Miguel.  According to the information available at the time the earthquake it was felt with maximum intensity V (moderate shaking) / VI (strong shaking) (Modified Mercalli Scale) in S. Miguel. The event was also felt on the islands of Santa Maria with intensity V and Terceira intensity III.
The major earthquake has been followed by multiple aftershocks, two of them with lower intensity encountered in S. Miguel.

Screen Shot 2013-04-30 at 09.53.10

The red bullets are showing the most recent seismicity as discussed in this report

 

Update 07:16 UTC : Almost all the agencies have now changed the Magnitude to 5.8, which makes this a strong earthquake. These kind of earthquakes so close to the islands are not happening very often, even when the Azores are considered a very seismic area.

Update 07:03 UTC : Geofon data are however mentioning a Magnitude of (only) 4.6, a whole lot of difference in between both parameters. We will change our alert color to green if the Geofon data are confirmed by other seismological agencies.

Update 06:59 UTC : The data we have received so far are indicating a very shallow depth. The epicenter location in the Ocean (if confirmed) will weaken the shaking impact considerably, but we cannot exclude damage on the nearby islands.

A strong earthquake very close to Sao Miguel and Santa Maria Island has shaken the Azores Islands

Screen Shot 2013-04-30 at 08.54.41

1394 km W of Lisbon, Portugal / pop: 517,802
65 km E of Ponta Delgada / pop: 20,056
41 km SE of Furnas, Portugal / pop: 1,599

Most important Earthquake Data:

Magnitude : 5.8

Local Time (conversion only below land) : Unknown

GMT/UTC Time : 2013-04-30 06:25:22

Depth (Hypocenter)  : 2 km

Depth and Magnitude updates in the list below.

Share your earthquake experience (I Have Felt It) with our readers.
Click on the "I Felt It" button behind the corresponding earthquake. Your earthquake experience is not only important for science, but also for people in the area as well as our global readership.

Refresh this list
SRC Location UTC Date/time M D INFO
EMSC Azores Islands Region Apr 30 10:41 3.3 2 MAP I Felt It INFO
EMSC Azores Islands Region Apr 30 09:39 3.2 5 MAP
EMSC Azores Islands Region Apr 30 08:53 3.2 8 MAP I Felt It INFO
EMSC Azores Islands Region Apr 30 06:30 3.7 5 MAP
USGS Azores Islands, Portugal Apr 30 06:25 5.9 10 MAP
  • Maia - I'm from Massachusetts in America and never experienced an earthquake been through blizzards hurricanes and tornadoes never an earthquake and to feel the house shake and things falling it was more fearful then what i went through in Massachusetts
  • GEOFON Azores Islands, Portugal Apr 30 06:25 5.8 10 MAP
    EMSC Azores Islands Region Apr 30 06:25 5.8 2 MAP I Felt It INFO
  • Maia, Santa Maria - Awaken by a noisy shake about 10-12 minutes ago. Must have been the clay-shingles in the roof. Brief survey revealed no damage.
  • Praia da Vitorio, Terceira - I felt my bed shaking, it saved me from being late to work.
  • Ponta Delgada - My house shook quite a lot.
  • Cabo da Praia - felt my bed shaking just after 6:20 am
  • Lagoa - Acordei com um barulho que fez e logo a seguir senti a cama a baloiçar por 5 a 7 segundos. (via emsc)
  • Ponta Delgada - It was very perceptible and long lasting (via emsc)
  • Arrifes - Felt well but not strong. People wake up. From my experientce I would sy that was intesity of III from Mercalli. (via emsc)
  • Vila do Porto - Awake during a deep sleep with the shaking and some noise.
  • Nordeste - Fiquei bastante assustada, e preparei-me para sair de casa, se necessário.
  • Capelas - Bed shaking. It seemed long and very perceptible but not too strong. A broom close to a wall fell to the floor.
  • Agua D'alto - First earthquake I ever felt, I was awake so I got full experience. Now, I thought earthquakes were more dangeorous, I mean this was 5.8 in Ritcher scale right? There should be somekind of training in these places. I didn't feel scared or in danger at all and I wouldn't consider that quake to powerfull... In my opinion only already-wrecked houses would fall. Are you sure it was 5.8??? ER : It was indeed a M5.8 with a moderate to max. strong shaking on your island. Earthquakes are however felt in
  • Ponta Delgada - I felt the bed shaking around 6:30 am which seemed to last for 8-10 seconds. My wife was not awakened by the movement.
  • Sao Roque - Felt the bed and the house shaking for a few seconds

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    SHARE YOUR EARTHQUAKE EXPERIENCE WITH US

    I felt the shaking *
    Country where you felt the earthquake *
    City/Village where you felt the earthquake *
    Street or suburb (area) where you felt the earthquake
    Latitude (area) where you felt the earthquake
    Longitude (area) where you felt the earthquake
    Shaking Strength *
    MMI II (Very weak shaking) ?
    People :
    Felt by persons at rest, on upper floors or favorably placed.
    MMI III (Weak shaking) ?
    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.
    MMI IV (Light shaking) ?
    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.
    MMI V (Moderate shaking) ?
    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.
    MMI VI (Strong shaking) ?
    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.
    MMI VII (Very strong shaking) ?
    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).
    MMI VIII (Severe shaking) ?
    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.
    MMI IX (Violent shaking) ?
    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.
    Tell us your experience and how many seconds the shaking lasted + let us know if your property has been damaged (even slight damage). (max. 500 characters)
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