Mexicali 7.2 Magnitude Earthquake Felt by 20 Million

SAN DIEGO, California, April 4, 2010 (ENS) – At least one person is dead and several homes have burned in northern Mexico after a magnitude 7.2 earthquake struck in Baja California at 3:40 pm local time Sunday. An estimated 20 million people in Mexico and three U.S. states felt the strong temblor, say scientists with the U.S. Geological Survey.

A man was killed when his home collapsed near the city of Mexicali, a civil protection chief told the Associated Press. More people are reportedly trapped in their homes, and a two-story parking garage collapsed in the border city.

Search and rescue teams with trained dogs and excavation equipment are trying to reach Mexicali from Tijuana about 100 miles to the west, but a landslide on the highway has blocked vehicle access.

Earthquake damage in Mexicali, Baja California. April 4, 2010. (Photo by Alberto Adame)

The epicenter of the quake was recorded 46.6 miles (75 km) south of the Mexico-U.S. border 16 miles southwest of Guadalupe Victoria in Baja, Mexico, and about 104 miles east-southeast of Tijuana, according to the U.S. Geological Survey.

USGS seismologists said the Mexicali earthquake is the strongest to hit the region in nearly two decades. They estimated that 20 million people in Mexico and in three U.S. states felt the quake, which rocked buildings from Tijuana to Los Angeles to Phoenix and was felt as far away as southern Nevada.

Its depth was measured at 6.2 miles along the boundary zone between the North American and Pacific plates.

Across the border from Mexicali in the U.S. city of Calexico, fire department officials reported damage to buildings in the older part of town. Gas lines were leaking and parts of the water system have been damaged.

In San Diego, the Sheraton Harbor Island towers were evacuated due to structural concerns, but an inspection by building engineers determined there were no major problems, said Maurice Luque of the San Diego Fire-Rescue Department.

“I couldn’t believe how long the earthquake lasted here in North County, San Diego,” said one resident. “It literally rolled on and on here. More than anything, I felt a bit seasick from the motion.”

Since earthquakes have been recorded instrumentally, only two similar sized earthquakes have been recorded in the area. The first was the 1892 earthquake estimated at magnitude 7.0 to 7.2 along the Laguna Salada fault just south of the border. The second was the 1940 Imperial Valley magnitude 6.9 earthquake which occurred in southernmost California.

Today’s event is located nearly in line with these earthquakes along the plate boundary, but is situated farther to the south. There are several active faults in the vicinity of today’s earthquake, and the particular fault that generated this quake has not yet been determined.

Faulting is complex in this region, because the plate boundary is transitional between the ridge-transform system in the Gulf of California and the continental transform system in the Salton Trough.

Most of the major active faults are right-lateral strike-slip faults with a northwest-southeast orientation, similar in style to the San Andreas fault to the north. Other faults in the vicinity with the same orientation include the Cerro Prieto fault and the Laguna Salada fault.

There have been three large aftershocks, including one that registered a 5.5 magnitude, and other smaller quakes, the USGS said.

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