RIDGECREST • The authorities have declared a state of emergency in Southern California's San Bernardino County, as seismologists expect more aftershocks to follow two powerful quakes that shook the region in just two days.

The proclamation, issued yesterday by California Governor Gavin Newsom, will give local agencies more access to resources that can help address the damage caused by the quakes and aftershocks, NBC Los Angeles reported.

Southern California was hit by its largest earthquake in two decades on Friday, a 7.1-magnitude tremor that rattled residents less than 48 hours after a 6.4-magnitude quake struck the same area.

Friday's shallow quake hit a sparsely populated area near the small town of Kern County's Ridgecrest city, around 200km north-east of Los Angeles.