Mexico: Preliminary earthquake report

Magnitude 7.8 near Tecomán, Colima, Mexico
Wednesday, January 22, 2003 at 2:06:35 (UTC)

Magnitude: 7.8

Time: Wednesday, January 22, 2003 at 2:06:35 (UTC)

Distance from:
13 km (8 miles) S (183 degrees) of Tecomán, Colima, Mexico
16 km (10 miles) SSE (147 degrees) of Armería, Colima, Mexico
45 km (28 miles) SSW (192 degrees) of Coquimatlán, Colima, Mexico
51 km (32 miles) SSW (199 degrees) of Colima, Colima, Mexico

18 deg. 48.4 min. N (18.807N)
103 deg. 53.2 min. W (103.886W)

Depth: 33.0 km (20.5 miles)

Quality: Error estimate: horizontal +/- 9.7 km; depth fixed by location program


The following is a revised release by the United States Geological Survey, National Earthquake Information Center: A major earthquake occurred IN COLIMA, MEXICO, about 30 miles (50 km) east-southeast of Manzanillo, Colima or about 310 miles (500 km) west of Mexico City at 7:06 PM MST today, Jan 21, 2003 (8:06 PM CST in Mexico). A PRELIMINARY MAGNITUDE OF 7.8 WAS COMPUTED FOR THIS EARTHQUAKE. The magnitude and location may be revised when additional data and further analysis results are available. There have been some reports of damage in the states of Colima, Michoacan and Jalisco. The earthquake was felt strongly in Mexico City.

Tectonic Summary:

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 moving Rivera Plate is moving north-west at about 2 cm per year relative to the the North American Plate and the faster moving Cocos plate is moving in a similar direction at a rate of about 4.5 cm per year.

There have been several significant earthquakes near the recent event. In 1932, a magnitude 8.4 thrust earthquake struck about 100 km to the north-north-west. More recently, on October 9, 1995 a magnitude 8.0 earthquake struck about 50 km to the north-west killing at least 49 people and leaving 1,000 homeless. The most deadly earthquake in the region occurred about 170 km to the south-east on September 19, 1985. This magnitude 8.0 earthquake killed at least 9,500 people, injured about 30,000, and left 100,000 people homeless.

Additional information about this earthquake can be obtained from the Universidad Nacional Autonoma de Mexico (National Autonomous University of Mexico) in Mexico City (52-5-622-4126). For additional information, see the USGS NEIC web page