The El Mayor cluster now contains many more events and covers a wider area.
The elmayor cluster is named for a mountain named Sierra El Mayor, 60 km
south of Mexicali, Mexico on the Mexico-California border. The cluster
crosses the U.S.-Mexico border, about 30 km into California. The cluster
includes the 7.2 Mw El Mayor – Cucapah earthquake on April 4, 2010, but
no other events are larger than 5.9. All events are observed to at least
10° epicentral distance. The region is heavily instrumented and location
calibration is robust enough for depth control to be done with a free
depth relocation for most events. A few events were unstable in a free
depth relocation and are set manually for the final relocation.