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27 January 2003, 04:15 PST

A mild earthquake occurred off the coast of Northern California about 87 miles WSW of Crescent City at 04:15 AM PST on Monday morning, January 27, 2003. This event has a local magnitude of 3.1 (ML).

25 January 2003, 20:59 PST

A mild earthquake occurred at 08:59 PM PST on Saturday night, January 25, 2003. This epicenter was located about 15 miles NNW of Quincy. This event has a local magnitude of 3.0 (ML).

21 January 2003, 19:06 PST

A major earthquake occurred at 06:06 PM PST on Tuesday evening, January 21, 2003. This event was located near the coast of Colima, Mexico. The surface wave magnitude for this event, averaged over the Berkeley Network, is 7.2 (Ms) (Northern California is close to the "null" axis for this earthquake.) The USGS National Earthquake Information Service reported a moment magnitude of 7.8 (Mw). The epicenter was located about 30 miles ESE of Manzanillo, Colima. The shaking was felt in the states of Colima, Michoacan and Jalisco, and strongly felt at Mexico City 310 miles away. At least 29 people were killed, 300 injured and about 10,000 people left homeless in the region near the epicenter.

This shallow earthquake occurred in a seismically active zone near the coast of central Mexico. The earthquake occurred near the juncture of three tectonic plates: the North American Plate to the north-east, the Rivera Plate to the north-west, and the Cocos Plate to the south. Both the Rivera Plate and the Cocos Plate are being consumed beneath the North American Plate. The slower subducting Rivera Plate is moving north-west at about 2 cm per year relative to the the North American Plate and the faster Cocos plate is moving in a similar direction at a rate of about 4.5 cm per year. (USGS National Earthquake Information Center) It is interesting to note that we have a similar situation along the Northern California, Oregon and Washington coasts where the subducting Gorda Plate and Juan de Fuca Plate fit in between the North Amercian and Pacific Plates.

20 January 2003 - 00:43 & 01:10 PST

A major earthquake occurred at 12:43 AM PST early Monday morning, January 20, 2003. This event was located in the Solomon Islands Region about 85 miles SE of Honiara. The surface wave magnitude for this event, averaged over the Berkeley Network, is 7.8 (Ms). The USGS National Earthquake Information Service reported a moment magnitude of 7.3 (Mw) for the earthquake. No significant damage or injuries were reported.

A mild earthquake occurred at 01:10 AM PST on Monday morning, January 20. This epicenter was located about 4 miles SW of Gilroy. The local magnitude determined for this earthquake is 3.0 (ML).

18 January 2003, 21:06 PST

A mild earthquake occurred at 09:06 PM PST on Saturday night, January 18. This earthquake was located about 1 miles ENE of The Geysers, south of Clear Lake, CA. The local magnitude determined for this event is 3.2 (ML).

15 January 2003, 20:53 PST

A strong earthquake occurred at 04:53 PM PST on Wednesday afternoon, January 15, 2003. This earthquake was located off the coast of Oregon, about 250 miles W of Coos Bay. The local magnitude for this event, averaged over the Berkeley Network, is 6.2 (ML). This earthquake was preceeded about 2 minutes earlier by a magnitude 4.9 foreshock, and followed by several aftershocks in the region, the largest two of which had magnitudes of 5.3. These events occurred along the Blanco Fracture Zone, one of several seismically active transform faults off the Oregon coast. It offsets the Gorda Ridge from the Juan de Fuca Ridge (ridges are spreading centers where new ocean floor is created). More information about the Blanco Fracture Zone is available here.

14 January 2003, 07:51 PST

A mild earthquake occurred at 07:51 AM PST on Tuesday morning, January 14, 2003. This epicenter was located off the coast of Northern California about 19 miles NW of Ferndale. The local magnitude for this event, averaged over the Berkeley Network, is 3.4 (ML).

13 January 2003, 06:47 PST

A mild earthquake occurred at 06:47 AM PST on Monday morning, January 13, 2003. This epicenter was located about 5 miles WSW of Gilroy. The local magnitude for this event, averaged over the Berkeley Network, is 3.0 (ML).

12 January 2003, 23:48 PST

A mild earthquake occurred at 11:48 PM PST on Sunday night, January 12. This earthquake was located about 2 miles NNW of Redding. The local magnitude determined for this event is 3.0 (ML).

9 January 2003, 07:20 PST

A mild earthquake occurred at 07:20 AM PST on Thursday morning, January 9. This epicenter was located about 14 miles SW of New Idria and 17 miles E of King City. The local magnitude for this earthquake is 3.2 (ML).

7 January 2003 - 08:40, 14:29 & 21:43 PST

At 08:40 AM PST a mild earthquake occurred about 3 miles ENE of Quincy. The local magnitude for this event is 3.0 (ML).

A moderate earthquake occurred at 02:29 PM PST on Tuesday afternoon. This epicenter was located about 3 miles S of Hollister. This event had a local magnitude of 4.6 (ML), and a moment magnitude determined at Berkeley of 4.3 (Mw).

Finally, a moderate earthquake occurred off the the coast of Northern California. The preliminary location placed the event 61 miles W of Petrolia; the revised location from UCB places it somewhat closer to the coast - approximately 40 miles W of Petrolia. This event occurred at 09:43 PM PST on Tuesday night. The local magnitude for the earthquake is 4.2 (ML), and the UCB moment magnitude is 4.4 (Mw).

2 January 2003, 08:15 PST

A moderate earthquake which occurred at 08:15 AM PST on Thursday morning, January 2, 2003. This epicenter was located in Southern California about 12 miles NE of Arvin, and 20 miles ESE of Bakersfield, CA. The authoritative magnitude for the event, published by Caltech and the USGS Pasadena, is 3.6. The local magnitude determined by UC Berkeley is 4.0.

UC Berkeley magnitudes tend to be higher for southern California events than the magnitudes determined by Caltech and the USGS Pasadena. This is due in part to differences in models used to correct for the decay of amplitudes with distance and in part to the more distant stations in our solution. Scientists at Caltech and UC Berkeley are currently working to develop to a new attenuation model which will apply to both northern and southern California.

1 January 2003, 00:00 PST

Happy New Year!