It’s all too perfect that there is new, creepy activity happening in the California fault lines just before Halloween.
Recent California Earthquakes
In recent weeks, California has had an uptick in seismic activity, some of which experts have linked to a creeping section of the San Andreas fault system. Most recently, Pleasant Hill and Hollister both experienced magnitude 4.5 and 4.7 earthquakes, respectively.
To have two 4.5 magnitude quakes in one week in California is a little unusual.
The Garlock Fault’s movement is known as “creep”: meaning that it is moving at a slow, continuous pace. Creep is typical among California faults, and creep could also trigger an earthquake nearby. The San Andreas fault has often had spells of creeping in reaction to other nearby earthquakes. Scientists are especially concerned about the San Andreas’s potential for disaster, but that’s not to say it’s the only cause for concern.
Can creeping fault lines cause earthquakes?
Fault lines are more closely tied together than you would imagine. A seismic event can ripple out and influence the delicate web of fault lines around it. Earthquakes of all sizes are a reality for California life, and what could set off the domino effect is unclear. This rise in seismic activity serves as an important reminder:
California faces more than a lack of rain. The Los Angeles Times declared that California is in an earthquake drought, and the end of the drought will bring destructive results.
When Will the Next Big Earthquake Strike?
In this L.A. Times article, experts paint a clear (and unsettling) picture of a big quake waiting to happen. In fact, California earthquakes are inevitable. We don’t know when or where, but we do know that an earthquake will happen:
“Earthquakes must happen at some point to relieve the immense tectonic forces that are pushing part of the state northwest toward Alaska and the rest southeast toward Mexico.”
While it could be nice to say this drought is good news–who doesn’t like a break from earthquakes, right? –it isn’t. A drought means that there has been more time for tension to build up in the earth’s crust without a way to relieve the tension:
“[There may be periods] where things get kind of all locked up and no earthquakes happen for a while. You store a lot of strain in the Earth’s crust. Once it gets going, it’s like a set of dominoes. You might get multiple events if you have enough strain energy stored in the crust because it’s been a long time since an earthquake.”
Tom Jordan, USC Professor
The New Earthquake Era
This drought also means that Californians aren’t necessarily prepared for a large-scale quake. The last California earthquake that was greater than 7 magnitude was in 1857. The 6.7 magnitude Northridge quake was in 1994 and the 6.9 magnitude Loma Prieta quake was in 1989. There are people alive today who have no personal experience with earthquakes of this size, and there isn’t anyone alive today that would have experienced a California quake as big as the earthquake of 1857.
First-hand experience of a major earthquake tragically brings awareness to the forefront, and few Californians have that experience. Earthquakes almost seem like a myth to some people in California despite the major earthquakes the Loma Prieta and Northridge quakes and other quakes that have struck other countries in recent years. Only 10% of California homeowners have earthquake insurance coverage, and many of those homeowners live within thirty miles of an active fault.
Experts say that it’s important to be prepared. There is, potentially, an entirely new era of earthquakes looming ahead with more frequent (or destructive) events.