It wasn't until after the devastating 1994 Northridge Earthquake that killed 57 people and caused $20 billion in damage that scientists discovered its origin: A previously-unknown fault line 10 miles underground.
Hoping to uncover the many still-undiscovered faults that crisscross Los Angeles, geologists have a plan to set off underground explosions, reports CBS News Correspondent Sandra Hughes.
They trigger sound waves that can detect rocks and materials along fault lines.
"We analyze the sound-wave energy that's generated by our underground charges and recorded at our seismographs in order to create catscan-like images of the subsurface, or sonogram-type images of the subsurface," explains Gary Fuis of the U.S. Geological Survey.
They want to set off explosions in 97 different locations in Southern California. It's the locations inside the city that have raised concerns. Many of the seven city park sites are in residential areas.
"One has to be extremely cautious before allowing explosions to take place in the city of Los Angeles," says city Councilman Mike Feuer. "I'm certainly hesitant to see those explosions take place in city parks, unless I can be certain these are safe."
"There is no possibility we can trigger earthquakes," counters Fuis. "The amounts of energies we use in these small underground charges are similar to a plane landing at LAX, a garbage truck bumping down a road."
Despite the desperate need to find earthquakes, it will take months for scientists to calm fears and convince officials that an underground blast is the best way to predict where the next big quake may hit.