A rash of moderate quakes shook the south end of the Salton Sea Sunday, and the largest quakes were felt from Orange County and San Diego east into Arizona.

'What we're seeing is a classic Brawley seismic swarm,' USGS seismologist Lucy Jones told City News Service. 'We haven't seen one of these since the 1970s, and there was another one back in the 1930s.'

Some buildings were evacuated in Brawley, a small farm town 115 miles east-northeast of San Diego. 'It's pretty bad, we had to evacuate the hotel just for safety,' said Rowena Rapoza, office manager at the Best Western Hotel there.

Jones said USGS seismographs and analysis computers were overwhelmed by the rash of rattling that began at sunrise, and reached a crescendo with a magnitude 5.3 quake just after 12:30 p.m. It was followed by a 4.9 shaker within two minutes.

'Our system is choking on so many earthquakes,' Jones said. 'This area of California is deep soils, and we do not get as precise data as we do over the rest of the state, and that makes our data a little less precise.'

Preliminary computerized USGS reports had indicated that three quakes larger than magnitude 5.3 had rattled out from Brawley at 12:30. That was later resolved by seismologists to be two quakes, magnitude 5.3 and 4.9, Jones told CNS.

The quakes were strongly felt at Borrego Springs, in San Dieg.