According to estimates by the USGS and Southern California Earthquake Center, a massive quake on the Puente Hills fault could kill from 3,000 to 18,000 people and cause up to $250 billion in damage. Under this worst-case scenario, people in as many as three-quarters of a million households would be left homeless.
One reason for the dire forecast is that both downtown L.A. and Hollywood are packed with old, vulnerable buildings, including those made of concrete, Jones said.
By contrast, a magnitude 8 “Big One” on the San Andreas fault — more than 30 miles from downtown L.A., on the other side of the San Gabriel Mountains — would cause up to 1,800 deaths, according to estimates.
The shaking from a quake in the center of urban L.A. would be so intense that it could lift heavy objects into the air, Jones said. It has happened before, near the epicenter of the 1989 Loma Prieta earthquake in the Santa Cruz Mountains. There, the shaking was so bad, “we found an upside-down grand piano.”
“That’s the type of shaking that will hit all of downtown. And everywhere from La Habra to Hollywood,” Jones added.
The violent motion would be amplified by the soft soil underneath the Los Angeles Basin and the valleys, which produces a jello effect as shaking waves wobble off the basin.