2 very strong dangerous earthquakes in the Gulf of California – Minor damage reported in Guaymas

Last update: April 13, 2012 at 4:06 pm by By

Earthquake overview : A very strong ridge earthquake has hit the sea floor of the Gulf of California. The shaking will be extended onto the coastal areas like the Mexican continent and Baja California peninsula
“I have Felt it” Reports –> see below + Let us know “how you have felt this earthquake”
To read the full story as it happened, we advise our readers to start at the lower part of the page (earthquake data).
Check also our Mexico-only earthquake list

Keep this page open or return regularly as we will be back with more details when they become available

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Update 13/04 – 16:04 UTC
A local Guaymas newsletter (Autónomo) reports damage to 2 schools and a house in Empalme. Empalme is more than 150 km from the epicenter !

Update 13/04 – 09:54 UTC
The staff of Civil Protection, Urban Infrastructure and SIUE (Ministry of Urban Infrastructure and Ecology) is conducting currently an inspection in the Guaymas area (150 km from the epicenter).
The local head of Civil Protection, Leon Gerardo Soto reported that home owners in the greater Guaymas area have calles the Civil Protection to report damage on their houses.
Regarding the City Hall (Palacio Municipal), he said that new cracks were found at the main entrance.


Palacia Municipal de Guaymas - Image courtesy english.realmexico.info

Update 21:12 UTC
* Cracks on walls in Guaymas, Sonora : People were calling newspapers and local media to report damages in their houses. El Palacio Municipal (Municipal Palace ,local government building) reported cracks on the principal entrance.
* Mexican Proteccion Civil has evacuated people from the beach as a precautionary measure

Update 17:17 UTC
* At least 60 Americans have asked their touring companies to be transferred away from their vacation location at Bahía de Kino.
* Proteccion Civil Mexico has reported that they have had NO reports of damage or injuries in Guerrero Negro.  One of the main reasons that this earthquake will have been harmless may have been the short duration of the shaking (10 seconds in Hermosilla)
- An ER reader living in Tucson, Arizona (USA) mentioned having felt the earthquake !

Strike-slip type of earthquakes

- Since the mainshock, the earthquake area has been hit by 6 aftershocks varying in strength in between M3.7 and M4.8.

- The earthquake was felt strongly. There have been 2 confirmed reports in San Luis of a VI intensity (72km from the epicenter). This means that there is the potential for VII-VIII in the epicentral area (damaging). (we are choosing to ignore a response of VII, which came 354km from the epicenter).

- Historic damaging earthquakes of similar magnitude have occurred once in the epicentral region with a M7.0 earthquake in 1954 causing no deaths and minor damage. This is a good sign for the region affected.

- Looking at the epicentral area – the location is very sparsely populated with only a few houses along the coastline apart from Santa Isabel.

- Mexican hypocenter (UNAM) is at M6.8 and 10km depth, under land.

- USGS hypocenter is at M6.9 and off the coast – there is little chance of a tsunami due to the fault mechanism.

- The area around Santa Isabel is most at risk from the USGS-based hypocenter with a possible shaking of VII. Some damage should be expected. Currently Agua de Soda and other towns closeby near the national park of Baja California are most at risk from the Mexican hypocenter which is below land.

- The Mexican Civil Defense who is responsible for Search and Rescue and first aid has reported that so far NO damage or injuries has  been recorded.

- Based on the Geofon data both earthquakes were strike-slip earthquakes (mainly lateral movement).

- The average shaking recorded in Hermosilla is MMI IV (based on 84 reports). The shaking in Guerrero Negro is MMI V (moderate).  Hermosillo is 10. km from the epicenter and Guerrero Negro 133 km. As explained before our attention goes to the immediate area of the epicenter (very shallow earthquake) – 30 to 40 km radius is at risk for eventual damage. Whether there will be damage or not will depend on how long both shakings have lasted and on the final earthquake data numbers.

- As the earthquake struck in a coastal area, NOAA has written in his latest report (for USA people mainly) : A strong earthquake has occurred, but a tsunami IS NOT expected along the California, Oregon, Washington, British Columbia, or Alaska coast. NO tsunami warning, watch or advisory is in effect for these areas. Based on the earthquake magnitude, location and historic tsunami records, a damaging tsunami IS NOT expected along the California, Oregon, Washington, British Columbia, and Alaska coasts.

- So far we have no news of the epicentral area.

- The earthquake happened just after midnight. Mexican news channels haven’t picked up the news yet.  Of course it is in the middle of the night in Mexico and people seem to have been used to the many earthquakes of the last 24 hours.

- The set of earthquakes in the Gulf of California have started with a M4.7 earthquake, followed 18 minutes later by a M6.2 earthquake and another 9 minutes later with a M6.9 earthquake (the most powerful so far)

- USGS has calculated that 3000 people will have experienced a very strong shaking and that 105,000 have experienced a strong shaking. Both these areas are at risk for eventual damage, especially because 9 minutes earlier another very strong earthquake struck the same area.

- The Mexican Servico Sismologico Nacional reports a magnitude of 6.8 with an epicenter below land. These makes this earthquake the most dangerous in 24 hours !

- Although it is a ridge earthquake, the epicenter of the M6.9 quake looks to be very close to the coast which makes this earthquake (the second very strong in a matter of 9 minutes) EXTREMELY DANGEROUS for shaking damage and fatalities. Let us hope that we are too pessimistic here. The kind of shaking will depend on the focal mechanism

- Following calculations by the USGS (providing that the earthquake data are correct) a MMI VII will have been experienced on the Baja California peninsula ! This means dangerous for the coastal areas experiencing this kind of shaking.

- The whole North American continent is currently moving in such a way that the earthquakes of the last 12 hours are somehow related (Mexico Sur, Mexico Gulf of California, Utah, Oregon) . Scientists will have a lot of work in examining eventual relationships however there is no certainty at all that a relation would exist (at least for a couple of these earthquakes)

- We are talking in this case about a Ridge earthquake, this means 2 separating plates who are hanging and suddenly get away from each other. Ridge earthquakes are typical for Middle Ocean locations

- The earthquake struck just after midnight

- We are currently collecting data


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“I Have Felt It” reports as received by Earthquake-Report.com
See below for all the received Earthquake Experience reports as received by earthquake-report.com


Most important Earthquake Data:
Magnitude : 6.8-6.9
UTC Time : Thursday, April 12, 2012 at 07:15:48 UTC
Local time at epicenter : Thursday, April 12, 2012 at 12:15:48 AM at epicenter
Depth (Hypocenter) : 10.3 km
Geo-location(s) :
134 km (83 miles) NE (48°) from Guerrero Negro, Baja California Sur, Mexico
162 km (101 miles) W (268°) from La Doce, Sonora, Mexico

Links to important maps
USGS Did You Feel It Map
Google satellite map showing the epicenter and the surrounding area
Historic earthquakes map
Seismic hazard map
Shaking map
Focal mechanism report
Human impact map
GDACS earthquake report
NOAA tsunami report

I Have Felt this earthquake

SRC Location UTC Date/time M D INFO
EMSC Baja California, Mexico Apr 12 07:15 6.3 60 MAP I Felt It
  • Sonora, Hermosillo - Very weak shaking indicated
  • Hermosillo Sonora Mexico - Light shaking indicated
  • Hermosillo - Very weak shaking indicated
  • Hermosillo, Sonora Mexico - My computer monitor and my fish tank were shaking and i heard a berry weard sound
  • Guaymas, Sonora - Woke up to the bed shaking lightly.
  • Guaymas, Sonora - Very weak shaking indicated
  • Hermosilla, Sonora - Temblor debil con vibracion de vidrios y movimiento de camas, estaba despierta por eso lo senti, mi gato no lo sintio porque estaba dormido.
  • Bahia de Kino Viejo, Sonora - Strong shaking indicated
  • Tucson Az. - Thought I heard someone opening doors
  • Hermosillo, Mexico - Sitting at my laptop just past midnight felt my chair moving underneath me twice! Crazy experience didn't know what it was till I found out about the earthquake.
  • Tucson AZ - felt house shake for a split second was absolutely crazy never experienced that before.
  • GEOFON Baja California, Mexico Apr 12 07:15 7.0 10 MAP I Felt It
    GEOFON Baja California, Mexico Apr 12 07:06 6.1 10 MAP I Felt It

     

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    SHARE YOUR EARTHQUAKE EXPERIENCE WITH US

    Enter Email (not compulsory)
    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
    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.
    Write your experience below + let us know if your property has been damaged (even slight damage) or if you have knowledge of any damage caused by this earthquake. (max. 500 characters)

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