Southern California is earthquake country. But if you’ve lived in the area for the last couple of decades, you might not know it.
Despite Thursday’s wake-up call 6.4 magnitude in a remote desert area near the town of Ridgecrest, Southern California has been experiencing an earthquake drought, scientists said Thursday.
The relative inactivity did not go unnoticed by one high-profile expert on California’s shakers.
“I think this would be a good time to remind you that if you have been experiencing earthquakes for the last 20 years in California, you have been experiencing an extremely quiet time in California history,” Caltech scientist Lucy Jones said.
Take note of that history:
The last time there was an earthquake above magnitude 6 in Southern California was 1999, Jones said.
The previous decade leading up to that had about eight magnitude 6s.
“This has been an extremely quiet, abnormal time,” she said.
Jones said the quake that shook the region on Thursday was actually more “normal” for what we should be expecting in Southern California, based on historical averages.
A quake of the Ridgecrest size, based on long-term history, should be coming once every five or 10 years in Southern California.
Yet, you’d have to go back to Oct. 16, 1999, for anything bigger. That’s when a magnitude 7.1 quake hit about 32 miles north of Joshua Tree.
Until Thursday’s Ridgecrest quake, it was the largest tremor to have hit the area since the 7.3-magnitude Landers Earthquake struck on June 28, 1992. And just this year, the 25th anniversary of the 6.7-magnitude Northridge Earthquake was remembered, along with its tragic toll of 57 people killed.
March 16, 2010: magnitude 4.4: Pico Rivera
May 17, 2009: magnitude 5.4: Yorba Linda
Jan. 28, 2002: magnitude 4.2 Simi Valley
Aug. 17, 1995: magnitude 5.4, 25 miles north of Ridgecrest
Jan. 17, 1994: magnitude 6.7, Northridge
So what does this all mean? Are we due? Is there energy building up on the faults throughout Southern California?
It may just come down to being aware.
Here’s what U.S. Geological Survey seismologist Robert Graves had to say about that: “Obviously any earthquake that occurs releases some of that tension. But there’s a tremendous amount that’s built up since the last major earthquake, which was in 1857 on the San Andreas.”
(That 1857 quake, just so you know, was the one that shook southern and central California on January 9, 1857, according to a Caltech chronology. It uprooted trees in the San Bernardino Mountains and caused the Kern River to flow backwards for a time. But because of the small population in California in 1857, there were only two deaths, one near Fort Tejon, where many buildings were destroyed, according to Caltech.)