The 18 May 2012 (Ms 4.5) Chapala Lake, Jalisco, Mexico Earthquake

Abstract:

The central part of Jalisco, Mexico has experienced at different times the occurrence of low magnitude earthquakes series. Although the effect of these earthquakes have been limited to relatively small areas have caused general alarm within the population and even in some cases true catastrophes (e.g. San Cristobal 1875). These groups of earthquakes that have lasted for weeks and even months have greater importance because they affect the most populous state area including the capital city of Guadalajara. An extraordinary example of these series of earthquakes occurred on 8 may 1912 that lasted until September. In the first 18 days 64 events were felt by residents of Guadalajara. Since then, there has been a relative seismic activity calm in the region.

This paper analyzes the earthquake of May 18, 2012 (03:07 UT) occurred at the West edge of Lake Chapala. While it's an event of low magnitude (4.5 Ms) it has the importance of having occurred just 60 km to the South of Guadalajara and for which instrumental data of first quality is available. The focus of the earthquake was located at 20.30 ° N and 103.49 ° W at a depth of 0 km using arrivals of P and S waves at 16 regional seismic stations. However, by the errors of localization inherent in the method focus could be in a range of 0 to 5 km deep. The mechanism of failure using the polarities of the first arrivals favors a clear faulting of dip slip type along a plane with strike = 227 °, Dip = 80 °, and Rake = 93 °. Waveforms analysis is being used to corroborate these results.