The earthquake that rocked Southern California over the weekend may have triggered several moderate quakes near the San Andreas Fault, seismologists said today.

The so-called Hector Mine earthquake tore a 25-mile-long gash from a dry lake through the Mojave Desert, displacing dirt roads and creek beds. Scientists upgraded the quake's magnitude from 7.0 to 7.1 today--a 25 percent increase in shaking.

Saturday's temblor, which struck at 2:46 a.m. in a sparsely populated stretch of desert, caused minor injuries on an Amtrak train that derailed.

Within hours of the quake, some seismologists were alarmed by a series of earthquakes as powerful as 4.0 that struck 120 miles away near the Salton Sea, a few miles from the massive San Andreas Fault.

"It's very clear that the faults in this area are talking to each other," U.S. Geological Survey seismologist Lucy Jones said. "It's not clear what exactly that pattern is," so scientists can't predict another quake resulting from this one.

Although most seismologists say there is no connection among the large quakes that have occurred recently around the world, some are considering links between the Hector quake and a 7.5-magnitude temblor that killed 27 people in Mexico last month, said Kate Hutton of the California Institute of Technology.

"There's a small minority who believe there may be a connection," she said. Hutton said she found the link between the Salton Sea and Hector quakes "more likely," considering the close distance between them.