Seismo-Watch

More Special Earthquake Reports

November 12, 2002

An earthquake registering M 4.2 occurred this morning in Central California near Parkfield. Reports indicate it was felt in the epicentral area but was not strong enough to cause any damage or injuries.

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According to the Northern California Seismic Network (NCSN) the earthquake measured ML 4.2 and occurred at 8:48 a.m. PST (16:48:25 GMT), November 12, about fifteen miles southwest of Coalinga and seven miles northwest of Parkfield along the northwestern portion of Middle Mountain, above the hard waters to Little Cholame Creek. See a Topozone topographic map or a MapQuest street map.

The focal point was at 8.4 km beneath the surface. UC Berkeley indicated a Moment magnitude Mw 4.2, and their fault plane solution suggested strike-slip motion along a northwest trending plane. See the UC Berkeley solution.

Foreshocks and Aftershocks
A small M 1.9 foreshocks occurred the day before. Uncharacteristically, only a light aftershock was recorded, consisting of a half dozen events in the M 1.0 range. Moderate jolts in this part of the country are usually followed brisk aftershocks sequences.

Felt Reports
Shaking was sharply felt in the epicentral area and mild tremors were felt as far away as Fresno, Visalia and Clovis on the east, Santa Maria on the south, and San Luis Obispo to Cambria on the coast. No reports were received from points north of Parkfield.

Preliminary data indicate residents felt a sharp jolt followed brief ground shudders. Did you feel this quake? Nothing toppled from tables or shelves.

Background
This was the first quake to register in the M 4.0+ range in this well-known place for earthquake activity since 1994.

The San Andreas Fault seems to always produce a few tremors registering M 1.0 or stronger near Parkfield every week (See the Seismo-Watch Central California earthquake report), but action has been slightly more active over the past few months.