Another earthquake swarm has been rattling the area southeast Salton Sea in the Imperial Valley. There have been over 1000 quakes since Saturday. The largest a 5.3 magnitude.
Dr. Lucy Jones, seismologist and founder of the Center for Science and Society took time out from visiting her grandchild to help us understand the swarm.
Jones says swarms are different than a quake where you have an earthquake and aftershocks, “In a swarm you have a group of earthquake that are all about the same size with the largest one not that much larger than the others and the biggest one is often not in the beginning of the sequence it’ll often be well into the middle of it.”
She says these swarms are happening on the Brawley Seismic Zone where swarms where there is a lot of thermal activity and liquid rock not too far below the surface.
Jones says they are common on this series of smaller connected fault lines, “The Imperial Valley has these types of swarms a lot and the largest we’ve seen in such a swarm is I think a 5.8 because the faults are smaller and the faults control how big an earthquake is because the faults are smaller and the faults control how big an earthquake is.”
She says they happen once a year on average, the last swarm happened in September of 2020, and largest one in that cluster was a 4.9 m but no big quakes followed.
“It does not make it more likely to be a fore-shock to a really big earthquake … this earthquake is too small to be changing the stress on the San Andreas, it’s small enough and far enough away that we aren’t worried about it doing something to the San Andreas.”
But she says the “Big One”, a 7.8 m or greater will come and it will be stronger in the Coachella Valley, “Think about shaking a bowl of jello, the bowl will go ping the jello flops back and forth and so you get amplification of the shaking when you have a loose soil and so you’re going to see very, very strong shaking because of the sand in the Coachella Valley.”
And while we can’t stop it, we can be prepared.
“However much water you have, get some more, we know that water pipes will break and that’s going to be a big problem but perhaps even more important than that is go talk to your neighbor about it, the people who get through the disasters are the ones who have friends and neighbors that they can work with and help each other,” says Jones.