4.2 Quake Near 2 Faults Prompts Low-Level Alert

A magnitude 4.2 earthquake near the intersection of the San Andreas and San Jacinto faults hit an area four miles northwest of San Bernardino on Saturday afternoon, and quake scientists declared a low-level precautionary alert.

No damage was reported in the 2:45 p.m. temblor, which was followed by several light aftershocks. It was felt in San Bernardino, Colton, Rialto and the San Bernardino Mountain resorts, the San Bernardino County sheriff’s office said.

Scientists declared the alert in accordance with a policy of the state and the U.S. Geological Survey that says safety authorities are put on notice whenever a quake in the 4 magnitude range occurs within five miles of the San Andreas fault.

But seismologists Egill Hauksson of Caltech and Lucy Jones of the Geological Survey said the D Alert called is the lowest of four possible classifications and that there was less than a 1% chance of a larger quake within the next 72 hours.

Hauksson said preliminary indications were that the epicenter of the quake was closest to the San Jacinto fault, which splits off from the San Andreas and proceeds southeast through Hemet to the Imperial Valley.

Quake probabilities released in 1995 by the Southern California Earthquake Center said the chances of a major quake along the San Jacinto fault are 40% in the next 30 years.