4.2 Quake Rattles Parkfield

A magnitude 4.2 earthquake struck Tuesday along the San Andreas fault in an area seven miles northwest of Parkfield in Central California where scientists have long forecast a strong quake in the magnitude 6 range.

The 8:48 a.m. temblor caused no damage or injuries. It occurred at a depth of five miles, the U.S. Geological Survey reported, and was very close to instruments drilled deep into the Earth in an experiment begun earlier this year to study the quake process.

Seismologist John Langbein, a supervisor of the work at Parkfield, said Tuesday’s quake slightly elevates the chance of a larger earthquake, predicted since 1985, occurring in the next few days. But he said there was only about a 1% possibility.

Parkfield is about midway between Los Angeles and San Francisco.