This map shows more than 245 aftershocks as Friday morning, ranging from 2.5 to 5.4.
The magnitude 5.4 quake, which hit Friday at 4:07 a.m., is the strongest one to rattle the region. It was followed by at least 36 more aftershocks as of 8:46am.
Thursday's 6.4 magnitude quake, centered southwest of Searles Valley in San Bernardino County, is the largest one to hit the region since 1999, according to the USGS.
It was felt as far south as Long Beach and as far north as Fresno and east to Las Vegas.