The 4.4 magnitude earthquake that was felt in many Southern California cities Monday fell on the Puente Hills Thrust Fault System, which is potentially the most destructive in the region.
Millions of people are directly on top of the Puente Hills Thrust Fault System, covering everything from USC to downtown Los Angeles to Pasadena and the northern parts of Orange County.
Research from 2005 said if a magnitude-7.5 earthquake hit that same fault system, thousands of people may die although a big earthquake like a 7.5 is only expected once every few thousand years and many safety improvements have taken place in buildings and cities since the research came out.
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“We had a six on this system in 1987. And it was like $350 million in damage and three direct deaths,” Seismologist Dr. Lucy Jones said. “When we’ve modeled what would it be to have a 7.5 on the Puente Hills Thrust, we get 10 times as much damage than we see for a 7.9 on the San Andreas because we have so many more buildings and people on top of an earthquake if it's Puente Hills.”
“This is a great reminder that all of Southern California is earthquake country. Every one of us in the Los Angeles Metropolitan Area is within five miles of an active fault."
Dr. Lucy Jones
“We consider it a dangerous fault, but it’s also a relatively slow moving fault,” Dr. Jones added. “There’s probably going to be 20 San Andreas earthquakes for every one time we have a Puente Hills earthquake.”
Monday’s 4.4 Magnitude earthquake happened in the same area as a 3.4 magnitude earthquake June 2, both produced aftershocks nearby.
Dr. Jones said that doesn’t increase the chances that a bigger one is on the way.
“This is a great reminder that all of Southern California is earthquake country. Every one of us in the Los Angeles Metropolitan Area is within five miles of an active fault,” Dr. Jones said. “And which one of those is going to go within our lifetime is random.”
“So I would say, if you want to look forward, how do you learn to live with earthquakes? You stop worrying about an individual fault. It’s going to be what it’s going to be,” Dr. Jones said.
Dr. Jones said instead take steps now to get your house ready in case the big one hits.
“Do what you can to make your house safer. I think maybe that's the final message,” Dr. Jones said. “Remember that most of the damage is preventable, and it's up to you to do it.”
