Following a swarm of smaller earthquakes near Bombay Beach in southern California, the United States Geological Survey is estimating a 1 in 100 chance of the San Andreas Fault rupturing in southern California before October 4, which could cause a devastating earthquake of epic proportions. The earthquake swarm began September 26 near the Salton Sea and included over 100 small tremors in the first day, the strongest measuring magnitude 4.3. However, the earthquakes didn’t stop, and around 40 more small earthquakes have shaken the region in the days since it began. USGS experts are concerned because the swarm of earthquakes is occurring on a system of fault lines that run perpendicular to the southern terminus of the San Andreas fault, increasing the possibility of agitating the much larger San Andreas fault and tipping off a massive earthquake.
Although seismologists can’t predict when or where an earthquake will strike, patterns in plate movement help establish theories about what might happen in the future, but without a specific date or location attached. Just shy of one year ago, a group of NASA geophysicists warned that California could be struck by a “mega earthquake” (one with a magnitude of 5.0 or higher) within the next 2.5 years. A year later, that quake hasn’t happened, but the scientific evidence hasn’t changed in a way that substantially impacts the prediction. Experts still believe a major earthquake in California could happen any day now.
The coastal state has been home to a number of earthquake swarms this year—clusters of tremors mostly registering less than M3.0. Swarms of small earthquakes are somewhat common for California’s central and southern regions, and the vast majority do not result in any substantial damage or injuries. However, this latest swarm near the Salton Sea has lasted longer than typical events, and seismologists are paying close attention as a result. Experts tend to agree that earthquake swarms such as these could agitate larger fault lines, including the famed San Andreas fault, and eventually kick off a much larger tectonic event.