Colima Mexico Earthquake

Update 1 | Summary
Posting Date: January 24, 2003, 1:00:00 PM

A major earthquake struck Colima, Mexico on Tuesday, January 21, 2003, at about 8:06 p.m. local time (Wednesday, January 22, 02:06 UTC). Official estimates of the moment magnitude vary from 7.8 according to the U. S. Geological Survey (USGS), to 7.4 from the Harvard University Centroid Moment Tensor (CMT) project. The quake lasted 45 seconds and was centered about 30 miles (50 km) east-southeast of the port city of Manzanillo, and about 32 miles (51 km) south-southwest of the state capital, Colima City. The earthquake was felt across western and central Mexico and as far as the capital, Mexico City, some 310 miles to the east. Preliminary indications suggest the earthquake occurred in a seismically active region at the juncture of three tectonic plates: the North American Plate to the northeast, the Rivera Plate to the northwest, and the Cocos Plate to the south. The moment tensor solutions from the USGS and the Harvard CMT project show this event as an oblique thrust, consistent with the oblique subduction of the Rivera or Cocos Plates under the North American Plate. There have been several significant quakes in the region, most recently a magnitude 8.0 earthquake about 30 miles (50 km) to the northwest in 1995. Initial reports indicate that most of the damage occurred in the states of Colima, Michoacan, and Jalisco. Thus far, about 29 people are reported dead, but those figures are expected to increase. In the hardest hit area, Colima City, portions of office buildings are reported to have collapsed, and about 40% of the structures in the capital suffered some damage. Almost all the older, adobe homes in downtown Colima are reported to be in ruins. Adobe, which is a form of sun-dried brick made with straw and asphalt, is particularly vulnerable to ground shaking. Currently, estimates are that some 10,000 homes in the state are damaged, with about 800 totally destroyed. At least 40 homes are reported to have collapsed in Guadalajara, Mexico's second largest city and capital of Jalisco. Bells fell from a church tower in the city. Two of the 29 deaths were reported in Jalisco. In Mexico City, buildings swayed but damage was limited to minor cracks on several buildings and brief power outages. Fearful residents took to the streets, reminded of the magnitude 8.1, Michoacán earthquake in 1985 occurred in the same area. That earthquake killed more than 10,000 people, caused about $5 billion worth of damage, and left 100,000 homeless in Mexico City alone. The AIR earthquake team has assembled the available information in the early aftermath of this event and has run simulations based on estimated epicentral location and magnitude. Maps of the total insurable loss and intensity representing five selected scenarios for the current event may be viewed on the Scenarios page of this website. Clients can also download event sets representing all scenarios. It is important to note that considerable uncertainty still exists with regard to the parameters of this event. AIR will continue to monitor the situation and post additional information as necessary.

Update 1 | Downloads
Posting Date: January 24, 2003, 1:00:00 PM