Slippage
Apparently there has been a biggish earthquake in Mexico City; the U.S. Geological Service estimate the earthquake had a preliminary magnitude of 5.9 and was centered in Michoacan, 125 miles southwest of the capital.
There were no initial reports of major damage in the city, and electric and telephone service weren’t interrupted..
There was another large quake in Mexico on July 29 :
The [Baja California] 5.8-magnitude temblor late Saturday was centered in the Sea of Cortes, which separates the peninsula from Mexico’s western coast, about 70 kilometers (45 miles) north of Loreto and 860 kilometers (535 miles) southeast of Tijuana, across the border from San Diego, California, according to the U.S. Geological
Survey in Golden, Colorado.
Mexico is located at the junction of a number of tectonic plates, as you can see from the above illustration. Mexico City has had devastating earthquakes before, and it’s not yet known what the strengrth of this latest is.
Here’s another map of the region, showing the areas most at risk, where pale blue is low and brown very high. Mexico City is at moderate risk of a seismic event, as is Southern California, but what these latest Baja and Mexico City quakes mean for the San Andreas fault remains to be seen.
