Maps available at http://earthquake.usgs.gov
On January 21, 2003, a major earthquake magnitude (M) 7.8 occurred at 8:06 PM CST in Colima, Mexico. The epicenter was about 30 miles (50 km) east-southeast of Manzanillo, Colima or about 310 miles (500 km) west of Mexico City. There have been reports of damage in the states of Colima, Michoacan and Jalisco. The earthquake was felt strongly in Mexico City.
There have been several significant earthquakes near this 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.
Last night’s 7.8 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 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.
On average, 18 major earthquakes (magnitude 7.0 to 7.9) and one great earthquake (8.0 or higher) occur each year worldwide. The USGS has sole responsibility for recording and reporting earthquake activity nationwide. The USGS is working to improve its earthquake monitoring and reporting capabilities through the Advanced National Seismic System. Full implementation of ANSS will result in at least 6000 new instruments on the ground and in structures. Once in place, the ANSS will provide emergency response personnel with real-time (within 5-10 minutes of an event) information on the intensity and distribution of ground shaking that can be used to guide emergency response efforts. Similarly, information on building "shaking" will equip engineers with the data they need to improve building designs in the future.