Scientists say it was a combination of things.
A city officials in Calexico says he is being pressured to remove police tape.
Only 12 percent of homeowners in California have a separate earthquake policy.
The effects of Sunday's quake were much felt more intensely in Mexicali.
At least one school makes the quake a teaching moment.
A team from the Salvation Army sent an emergency Mobile Feeding Unit to El Centro and Calexico, offering food and water to those who need it.
Surveillance cameras caught Sunday's quake as it happened.
Even as the recovery begins from Sunday's 7.2 temblor, the aftershocks continue.
Brothers traveling during Sunday's quake photograph a surreal sight.
Aftershocks rattled the region Monday in the wake of Sunday's major quake.