Tuesday’s California earthquake is unlikely to be a “foreshock” for a larger one, the expert says
An earthquake that shook parts of the San Francisco Bay Area on Tuesday could lead to aftershocks that could last for days or longer.
The 5.1 magnitude earthquake struck just before noon southeast of San Jose, near Alum Rock. It was widespread throughout the Bay Area. People as far away as San Diego and Lake Tahoe reported shaking.
A few hours after the quake, FOX Weather spoke to Kimberly Blisniuk, Ph.D., an earthquake geologist at San Jose State University, about the likelihood of more aftershocks.
“It’s based on the magnitude scale, so it’s 67% of a magnitude 3 or higher,” Blisniuk said. “If we hit strength 5, which is what we just felt, there’s a 2% chance.”
As of Wednesday morning, the US Geological Survey’s forecast for a magnitude 3 or greater quake was 21% within one day and 45% within a week. The prediction for an earthquake with a magnitude greater than 5 was less than 1%.
At least three other tremors, ranging in magnitude from 2.7 to 3.5, were reported in the area where the tremors took place on Tuesday.
Blisniuk said Tuesday’s tremors occurred along the Hayward-Calaveras Fault, part of the larger San Andreas Fault system.
“These faults are basically adjusting to movement between two major tectonic plates,” Blisniuk said. “The two plates are the North American Plate and the Pacific Plate.”
According to the USGS, the Calaveras Fault last caused a significant earthquake in October 2007. That was a magnitude 5.4 quake near Alum Rock.
According to the National Earthquake Information Center, California experiences two or three earthquakes each year that can cause significant damage and measure magnitude 5.5 and higher.