New Delhi, July 1 -- For those trapped in rubble after an earthquake, survival depends on many factors, including weather and access to water and air.

If their injuries aren't too severe, victims can survive for a week or more, assuming the weather isn't too hot or cold, experts say.

In Venezuela, rescue teams have been racing against the clock to pull survivors from the rubble after two powerful earthquakes shook the northern state of La Guaira last Wednesday. More than 770 buildings were totally or partially collapsed from the earthquakes, and aftershocks continued to shake the region.

Most rescues happen in the 24 hours after a disaster. The chances of survival drop with each day after that, experts say. Most victims are badly injur...