SAN FRANCISCO — A 7.1-magnitude earthquake rattled Southern California on Friday night, one day after the strongest recorded quake there in 20 years had struck — and seismologists warned that further episodes are expected.

The United States Geological Survey reported that the latest earthquake’s epicenter was in the Mojave Desert, 11 miles from Ridgecrest — near where a 6.4-magnitude quake had hit about 36 hours earlier. Since Thursday’s earthquake, the area had been jolted by a series of rolling aftershocks, including one of a 5.4 magnitude that had roused Californians on Friday morning.