Moderately strong earthquake M6.2 rocked Mexico 21st August 2013

 A moderately strong earthquake shook Mexico's capital Wednesday, but there were no immediate reports of injuries or damages. The U.S. Geological Survey said the quake had a magnitude of 6.2 and was centered on the Pacific coast, near the resort of Acapulco. There was also another after shock of M5.3 lagging of about 32 minute with main shock.

Buildings swayed in the capital and some people evacuated buildings as an earthquake alarm sounded. The alarm also went off for a second, smaller quake a few minutes later. Mexico City is vulnerable even to distant earthquakes because much of it sits atop the muddy sediments of drained lake beds that quiver as quake waves hit.

Read More

Confirmed 1906 San Francisco Earthquake fault after century

In 1906 there was a great San Francisco M7.7 Earthquake and fire following earthquake, that cause almost 664 casualties and 225,000 homeless among 400,000 population. More than 28,000 buildings collapsed and loss of more than $400 million of monetary value.

San Andreas fault earthquake cut a trench in 1906 through Portola valley. Seismologists and Geologists are on debate about the source of this earthquake due to poorly reproduced historical map. They are debating for the location of fault that cause earthquake in 1906 was in east and west. Now, Chester Wrucke, a former U.S. Geological Survey geologist, and his son Robert Wrucke, open up the cover to all geologist about rupture. They confirms only west side fault was ruptured during earthquake and also they find the exact location of fault that crosses Alpine road. They compared the 1906 photos to publicly available bare earth lidar imagery of the valley, tracing the historic ruptures onto the modern topography. Bare-earth lidar is an airborne laser measurement technique that results finely detailed topography, free of trees and brush.  

Some photographs of that earthquake are here 

Read More