By Lizbeth Diaz and Tim Gaynor
MEXICALI, Mexico (Reuters) - Families huddled in parks and parking lots in the northern Mexican border city of Mexicali on Monday after aftershocks from a big earthquake led them to sleep out in debris-strewn streets.
Two people died and more than 200 people were injured when a 7.2 magnitude quake rocked the Mexico-California border area on Sunday afternoon, Baja California Gov. Jose Osuna told a news conference.
The tremor, felt as far north as Los Angeles, cracked main roads, toppled electricity posts and knocked down an empty multi-storey car park under construction in Mexicali, a prosperous city and busy border crossing. One person was crushed in a collapsed house, the other hit by a falling wall.
Osuna said towns south of Mexicali near the quake's epicentre could be harder hit and 3,500 people whose houses collapsed or were badly damaged would be moved to shelters.
The area was rattled by more than 80 aftershocks in the hours following the quake, the U.S. Geological Survey said.
"With the number of aftershocks we've had, the likelihood of another 6 or 7 magnitude earthquake is very real," Erik Pounders, a USGS geologist, said. "There might be a few structures that just barely made it though and the second one could be the straw that breaks the camel's back."
Hundreds of people camped out overnight as smaller tremors shook buildings with cracked floors, walls and broken windows.
"I wasn't going to put my family at risk. Lots of homes have cracks," said Fermin Garcia, a teacher who slept with her family in a tent pitched between two shopping centres.
Broken gas pipes sparked a number of fires on Sunday, and darkened streets in Mexicali triggered car accidents, but no major buildings appeared to have collapsed.
Power was mostly re-established on Monday, but many state-run hospitals still lacked electricity and lay patients out on beds in parking lots due to worries over cracked walls.
A highway connecting Mexicali with the nearby border city of Tijuana on the Pacific coast was ruptured by a crack at least a metre (3 feet) deep, according to a Reuters witness.
A liquefied natural gas import terminal south of Tijuana was not damaged however, operator Sempra Energy said.
President Felipe Calderon will visit Mexicali, home to more than a million people and a centre for food processing and assembly-for-export plants, later on Monday.
AFTERSHOCKS
Vacationers returning from Easter holidays were stuck in traffic jams and motorists reported difficulty finding fuel.
"Thank God nothing happened to us. Now we just have to wait until the police let us fuel up," said Maria Lopez, who had been waiting four hours to buy fuel to drive to Tijuana.
Sunday's quake rattled nerves in the United States and across tremor-prone Latin America which has been shaken by devastating earthquakes in Haiti and Chile this year.
The relatively shallow quake was centred in a lightly populated area some 30 miles (48 km) to the southeast of the city. For several hours aftershocks rocked the area.
Over the border in the U.S. town of Calexico, eight downtown blocks were closed off as Border Patrol agents helped police secure the area against looters. Stores had leaning awnings, smashed windows and broken vases in window displays.
"It was violent, like the earth was mad ... My home was shaking very violently, pictures coming off the walls, then the TVs came down," said local firefighter Channing Dawson.
Earthquakes of 7.0 can do serious damage to urban areas.
Some parts of San Diego reported minor structural damage and callers to local radio said the rolling tremor made it hard to keep cars on the road. In Los Angeles, buildings swayed.
Southern California with its myriad geological faults is prone to frequent quakes and many residents fear the next big one. The last to cause major damage was the 6.7 magnitude Northridge quake in 1994 that left 57 dead and 9,000 injured.
(Additional reporting by Mica Rosenberg and Veronica Sparrowe in Mexico City; Writing by Catherine Bremer, editing by Alan Elsner)
