Worryingly, the section of the San Andreas Fault near the Salton Sea hasn’t experienced a huge event since the 17th century. However, these recent swarms and the discovery of a new fault section beside it doesn’t necessarily make the long-term prospects for a large earthquake any more or less likely.
True, the quake swarm did temporarily increase the chance of a major earthquake happening in the region fairly significantly for a day or two, but now that we know there’s a new fault in the region, perhaps any “big event” would be localized to this new relatively small one anyway.
Then again, the region is thought to suffer from so-called “double-fault” earthquakes, where the stress release from one could trigger a connected fault to jut forwards. It’s likely this happened during an 1812 event wherein the San Jacinto Fault jutted forwards, which induced part of the San Andreas Fault to rupture immediately afterwards. Could this new, minor fault’s future rupture set off San Andreas?
In sum, there’s a lot left to learn. We only recently found out that the Moon of all things is causing tens of thousands of incredibly small quakes within the San Andreas Fault every single year, after all. The big one will happen, and with each day that passes, it becomes more likely that it will be all the more destructive.
The best plan of action is to reinforce LA and San Francisco’s infrastructure, while paying attention to these sorts of studies delving deep into the secrets of San Andreas. Now seismologists have a new fault to keep an eye on.
Downtown Los Angeles awaits the big one. ESB Professional/Shutterstock