Western Mexican states hit by multiple aftershocks and earthquakes

The road runs the entire length of the Baja Ca...

Baja California Peninsula - Image via Wikipedia

The Mexican western states of Sonora, Baja California, Nayarit and Chiapas have been hit the last 24 hours by multiple earthquakes and aftershocks.
Everything seems to be moving and more tectonic movements may be expected.
4 different main areas can be defined.
a) The waters of the Gulf of California
With an epicenter in the coastal waters and a limited magnitude these earthquake can be categorized as safe.
b) The Sonora desert
The greater area of the massive M 7.2 earthquake from  April 4.  The epicenter of this earthquake was located more to the north in de border area between Mexico and the United States. Most of the aftershocks have an epicenter in unpopulated (beautiful!) desert areas.
c) The subduction zone of the Islas Marias islands
Active since a couple of weeks in various places and more or less in the greater Puerto Vallarta, Manzanilla zone.
Potentially dangerous if a shallow earthquake would strike nearer to the coastline.
d) Chiapas province
Regular (mostly deep) earthquakes with Magnitudes of +5. Harmless because of the depth of the hypocenter.

Overview of the  M +4 earthquakes from the last 24 hours (most recent above) (All times in UTC)

M 4.2      2010/09/15 08:21    Depth 10.0 km GULF OF CALIFORNIA
Third shock 8 seconds after the M 4.4 shock, in the middle of the peninsula

M 4.4      2010/09/15 08:13    Depth 10.0 km
GULF OF CALIFORNIA
Second shock only 2 minutes later, but under the peninsula

M 4.4      2010/09/15 06:46    Depth 10.0 km GULF OF CALIFORNIA
Light earthquake in the coastal waters of the Baja California peninsula. The whole area is very active the last couple of days.

M 4.7      2010/09/15 06:09    Depth 0.4 km     BAJA CALIFORNIA, MEXICO
Please also read the detailed page of this earthquake – Click here

M 5.1      2010/09/15 06:05    Depth 96.1 km CHIAPAS, MEXICO

Moderate but fairly deep and harmless earthquake near San Juan Custepeque , Chiapas Mexico

M 5.9      2010/09/14 23:32    Depth 36.0 km     ISLAS MARIAS REGION, NAYARIT, MEXICO
Click on this link for an extensive earthquake report

M 5.0      2010/09/14 10:52     Depth 10.0 km     BAJA CALIFORNIA, MEXICO
Click on this link for an extensive earthquake report

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Very powerful earthquake in the Mexican coastal waters

Puerto Vallarta at night

Puerto Vallarta at night - Image via Wikipedia

Earthquake Report comment :
The earthquake epicenter (preliminary) is located at a distance of around 113 km from Puerto Vallarta.
GDACS has just issued a GREEN earthquake report = very limited chance on damage and injuries.
The epicenter of the earthquake is just on top of a subduction zone.
The locations most at risk are the Islas Marias (Mexico).
Isla María Cleofas is located only 10 km from the epicenter.
USGS expects a Mercalli V to VI on the islands.
Based on the satellite pictures we can conclude that Isla María Cleofas is unpopulated.
The islands are inhabited by 1,116 people (latest census).
The coastal towns like Puerto Vallarta will experience a weak to light shaking.
Earthquake Report calls this earthquake potentially dangerous for the neighboring islands only (Islas Marias).

Islas Marias (wikipedia information)

The Islas Marías (“Mary Islands”) are an archipelago of four islands that belong to Mexico. They are located in the Pacific Ocean, some 100 km (60 miles) off the coast of the state of Nayarit. They are part of the municipality (municipio) of San Blas, Nayarit. As of 2006, the islands are still being used as a penal colony, containing the Islas Marias Federal Prison. The islands have an aggregate area of 244.970 km². 1116 people lived on Isla María Madre as of the census of 2005. The other islands are uninhabited. The main settlement is Puerto Balleto, with a population of 602.

Isla María Madre, the northernmost island, is the largest, with a surface area of 145.282 km². It houses the Islas Marías Federal Prison which was established there in 1905. The other two islands are Isla María Magdalena (70.440 km²) and, further south, Isla María Cleofas (19.818 km²). They were named after three women called Mary in the Biblical New Testament: respectively, Mary, the mother of Jesus, Mary Magdalene, and Mary, the wife of Cleopas.

The smaller island, Isla San Juanito, with an area of 9.105 km² lies off the north coast of Isla María Madre.

Most important Earthquake Data:
Magnitude : Mi 5.9
Tuesday, September 14, 2010 at 05:32:02 PM at epicenter
Depth (Hypocenter) : 36 km
Geo-location(s) :
10 km from Isla María Cleofas
103 km (64 miles) W (271°) from Las Varas, Nayarit, Mexico
113 km (70 miles) WNW (303°) from Puerto Vallarta, Jalisco, Mexico

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 Shaking map
USGS historic earthquakes map
USGS Pager map
GDACS Green Earthquake Alert (Global Disaster Alert and Coordination System)

* GDACS (Global Disaster Alert and Coordination System) provides near real-time alerts about natural disasters around the world. GDACS is a Joint Initiative of the United Nations and the European Commission

QuakeSOS has been developed to help actively people who are caught in an earthquake + delivers "Earthquake Report" information on your iPhoneQuakeSOS is a FREE iPhone application developed by Armand Vervaeck, the creator and main contributor to Earthquake Report. The Application simplifies immediate group communication to friends and family members (with your exact GPS location) and is constantly feeding the users with “Earthquake Report” news. Together with your own family and friends, QuakeSOS will be your closest earthquake friend.

Mexico – M 6.1 – Strong seaquake at a safe distance of Puerto Vallarta and Manzanillo

Fault zones of the Mexico August 24, 2010 earthquake - courtesy EMSC

Earthquake Report comment :
A strong shallow seaquake struck right on the fault line where the Pacific plate and the smaller Cocos plate collide.  The epicenter was though on a safe distance of almost 300 km out of the Mexican coast.
The earthquake was felt by some as a weak shaking, with of course no damage or injuries.
In this area, it is not the main fault line where today’s earthquake occurred (collision of Pacific and Cocos plate) which causes the highest risk, but the fault line closer to the coast where the Cocos plate and/or the smaller Rivera plate subducts under the North American plate (the steep sea ridge can clearly be seen on the Google satellite map and on the above fault line map). The biggest movement comes from the Cocos plate who travels at a rate of 40 mm/year under the North American plate.

On January 22, 2003 a large massive earthquake struck the coastal waters only 50 km from Manzanillo. This earthquake was also called the Colima earthquake (area name).
At least 29 people killed, 300 injured, about 10,000 homeless, 2,005 houses destroyed and 6,615 damaged. Most of the deaths and damage occurred in the Villa de Alvarez-Colima area. Extensive damage (VIII) at Colima and Tecoman.
Landslides closed a segment of the Colima-Guadalajara Highway and the port at Manzanillo.  A local tsunami of about 1 m  was recorded at Manzanillo.

Seismogram of the August 24, 2010 earthquake in the Pacific Ocean near the Mexican coast

The most deadly earthquake in the region occurred about 170 km to the south-east on September 19, 1985. This magnitude 8.0 earthquake (also called the Michoacan earthquake) killed at least 9,500 people, injured about 30,000, and left 100,000 people homeless.

Most important Earthquake Data:
Monday, August 23, 2010 at 07:12:00 PM at epicenter
Depth (Hypocenter) : 10 km
Geo-location(s) :
290 km (180 miles) SW of Puerto Vallarta, Jalisco, Mexico
315 km (195 miles) W of Manzanillo, Colima, Mexico

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 Shaking map
USGS historic earthquakes map
GDACS Green Earthquake Alert (Global Disaster Alert and Coordination System)

* GDACS (Global Disaster Alert and Coordination System) provides near real-time alerts about natural disasters around the world.  GDACS is a Joint Initiative of the United Nations and the European Commission

QuakeSOS has been developed to help actively people who are caught in an earthquake + delivers "Earthquake Report" information on your iPhoneQuakeSOS is a FREE  iPhone application developed by Armand Vervaeck, the creator and main contributor to Earthquake Report.  The Application simplifies immediate group communication to friends and family members (with your exact GPS location) and is constantly feeding the users with “Earthquake Report” news. Together with your own family and friends, QuakeSOS will be your closest earthquake friend.

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