A swarm of more than 20 moderate- to small-magnitude earthquakes
occurred 35 miles south of Calexico, CA, on the evening of 30 June and
morning of 1 July 2012. The swarm began with a M4.6 temblor at 8:25 pm
Saturday; the largest quake was a M4.7 at 11:36 pm later that evening.
Though poorly constrained the depth to focus was approximately 10 km (6
miles). There were no reports of damage from the nearby communities of
Guadalupe Victoria and Mexicali both of Baja California, Mexico. [Right, June-July
2012 earthquake swarm at south end of Sierra Cucapah in Baja
California, Mexico. Blue boxes represent earthquake epicenters. Map from Advanced National Seismic System, USGS]
Most of the 20+ events ranged from M1.5 to M3.0. The swarm occurred
at the south end of the Sierra Cucupah along the projection of the
Laguna section of the Elsinore fault zone that trends NNW from Baja
California to California. On 4 April 2010, a M7.2 earthquake occurred
very near to the locus of this swarm.
[cross-posted from AZGS's earthquake blog - "Groundswell"]