A magnitude 7.1 earthquake struck Southern California Friday night, the second major temblor in less than two days and one that rocked buildings across Southern California, adding more jitters to an already nervous region.
The quake was centered near Ridgecrest, the location of the July 4th 6.4 magnitude temblor that was the largest in nearly 20 years.
There were reports of Friday night's quake causing some fires and other damage in Ridgecrest, said emergency officials on the scene.
In Trona and Ridgecrest, two Mojave towns shaken by this quake and the previous one, residents answered their phones frantically and in fear.
"They're saying the ground split," said Winter Wilson, who was driving home to Trona from Bakersfield, her voice shaking. "They made me promise not to come."
The shaking was less intense in the Los Angeles metro area, and there were no immediate reports of major damage or injuries.
The 7.1 quake occurred on the same fault system as the 6.4 temblor that is now being considered a foreshock. It was further away from Los Angeles, though still in the Owens Valley.
"This happened at the end of the zone that moved previously," said retired USGS seismologist Lucy Jones.
It has already been followed by several aftershocks, some 15 miles to the northwest, Jones said. She said the fault is likely to be 25 to 30 miles long.
"The fault is growing," Jones said. "We ruptured a piece in the first earthquake (the 6.4 on Thursday), we ruptured a piece in the 5.4 (the aftershock yesterday), and we've ruptured more now."
The epicenter of Friday's quake seemed to be deeper than Thursday's large temblor _ Friday night's intensity, which scientists use to measure the amount of shaking, was absolutely greater Friday night, Jones said.
When Thursday's quake hit, scientists had warned that it could lead to an even larger quake. Ridgecrest has been rattled by more than 17 magnitude 4 quakes and at least 1,200 aftershocks since Thursday. A magnitude 5.4 aftershock occurred earlier Friday morning_ strong enough to awaken some residents of Los Angeles about 125 miles away.
Seismologists said Friday evening's temblor appeared to be part of the same sequence.
Friday's quake was larger in magnitude than the destructive 1994 Northridge quake, which measured 6.7 magnitude. But that temblor occurred in an urban area, while this week's huge quakes occurred 100 miles from L.A.
A 7.1 quake in 1999 hit the Hector Mines area of the Mojave Desert. Because of its distance from Los Angeles, it did not cause major damage or injuries.
The July 4 earthquake had ruptured along a length of fault 10 miles long, from a remote point northeast of Ridgecrest, a city of 29,000 people, and continued southwest almost all the way to the city limits, scientists said.
The aftershocks will probably "go on for months, if not years," California Institute of Technology seismologist Egill Hauksson said Friday.
