Two Small Earthquakes Shake Imperial County

A pair of small aftershocks rattled parts of the Coachella and Imperial valleys Sunday, according to automated seismographs operated by the USGS and California universities.

The quakes were among thousands of substantial aftershocks to the 7.2 magnitude El Mayor-Cucupa earthquake, which rattled Southern California and northern Baja California on Easter Sunday, April 4. That quake killed two people in Mexicali and caused about $100 million damage in Imperial County, the USGS said.

The first aftershock registered 3.7 at 11:04 a.m., and was centered 25 miles south-southeast of Mexicali.

The second, at 11:36 a.m., located 9 miles east-southeast of the small southeast San Diego County town of Jacumba, and was originally reported as a 3.5. Its magnitude was raised to 3.9 by seismologists after they examined data that had been first interpreted by computers.

The giant Easter quake spawned several aftershocks every day, but the frequency of those over 3.0 has been dropping, the USGS said. The largest in the past week were two quakes — magnitude 4.7 and 4.6 — recorded Thursday morning.