Central Mexico and Gulf of California Earthquakes: M6.9

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Mexico’s Tectonic Setting

Mexico is prone to earthquakes because of its location, where a number of the earth’s tectonic plates converge. The country itself is largely located on the North American Plate, with the Caribbean Plate abutting it in the east. In the south and west the smaller Cocos Plate is being forced against the North American Plate and to the north and west the Pacific Plate moves laterally past the North American Plate.

Subduction at a destructive boundary (image from USGS)How plate sudbusction

Subduction at a destructive boundary: Image courtesy of USGS

Such complicated interactions have left Mexico vulnerable to earthquakes of different types. In the south, the boundary between the Cocos-North American plates is a destructive boundary: here, the convergent movement and the difference in density mean that the Cocos Plate is forced downwards beneath the North American plate, with earthquakes resulting when the tension between the two plates is released.

California’s Tectonic Setting

California’s quake may appear related, but the different settings render the possibility unlikely. The boundary between the Pacific and North American plates in the north of the country is different in nature and is called a conservative boundary. Here, the plates have moved laterally past one another at an average speed of around 5mm per year for millions of years and form the southern part of the major and complex series of faults known as the San Andreas Fault System.

California Quake Related to Mexico Quakes?

Although it can be argued that any major plate movement will have repercussions elsewhere as release of tension on one part of a plate boundary alters the dynamics, the USGS notes that the earth’s crust is ‘not rigid enough to transfer stress fields efficiently over thousands of miles’. Bearing in mind both the distance and the different types of plate boundary, it isunlikely that the earthquakes in the Gulf of California are related to the series further south.

Sources

Smithsonian Institute. This Dynamic Planet Interactive Map. Accessed April 12, 2012.

US Geological Survey. Earthquake Hazard Program Latest Earthquakes M5.0+ in the World – Past 7 days. Accessed April 12, 2012.

USGS. Earthquakes, Faults, Plate Tectonics, Earth Structure. Accessed April 12, 2012.

USGS. Understanding Plate Motions. Accessed April 12, 2012.

US Library of Congress. Mexico Earthquakes. Accessed April 12, 2012.

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