LA HABRA, Calif. — Scientists say a bigger earthquake along the lesser-known fault that gave Southern California a moderate shake Friday could do more damage to the region than the long-dreaded ‘‘Big One’’ from the more famous San Andreas Fault.

The Puente Hills thrust fault, which generated Friday night’s magnitude-5.1 quake centered in La Habra and well more than 100 aftershocks by Sunday, stretches from northern Orange County under downtown Los Angeles into Hollywood — a heavily populated swath of the Los Angeles area.

A magnitude-7.5 earthquake along that fault could prove more catastrophic than one along the San Andreas, which runs along the outskirts of metropolitan Southern California, seismologists said.


The US Geological Survey estimates that such a quake along the Puente Hills fault could kill 3,000 to 18,000 people and cause up to $250 billion in damage. In contrast, a larger magnitude 8 quake along the San Andreas would cause an estimated 1,800 deaths.

In 1987, the Puente Hills fault caused the Whittier Narrows earthquake. Still considered moderate at magnitude 5.9, that quake killed eight people and did more than $350 million in damage.

Part of the problem with the potential damage is that the fault runs near so many vulnerable older buildings made of concrete in downtown Los Angeles and Hollywood. And because the fault, discovered in 1999, is horizontal, heavy reverberations are likely to be felt over a wide area.

In Yellowstone National Park on Sunday, a 4.8 earthquake shook the northern part of the park, officials said.

There were no immediate reports of damage.