A magnitude 7.1 earthquake struck southern California on Saturday at around 1:19 pm, with a reported epicentre around 16km to the northeast of the town of Ridgecrest—the second major quake to hit the region in two days.
Per the Washington Post, Kern County Fire Chief David Witt said that no deaths had been reported in the region, though county and state officials said there were reports of multiple structure fires, widespread power outages, cracked roads, and water and gas line ruptures.
Kern County, where Ridgecrest is located, had already declared a state of emergency after a magnitude 6.4 earthquake that had already qualified as one of the strongest in years hit nearby on Friday.
The 7.1 quake was the strongest with an epicentre in the state since the 1999 Hector Mine quake in the Mojave Desert, according to the Los Angeles Times, though a quake in 2010 in Mexico near Mexicali scored 7.2 and was felt across the border.
The mainshock began at the corner. We think the NE fault moved first, pulling away from and destabilizing the NW fault.
— Dr. Lucy Jones (@DrLucyJones) July 4, 2019
“We do feel like there is damage, but we don’t know the extent of it yet,” Witt told reporters on Saturday. “Nobody was trapped, no major collapses that we know of, but we are out there searching.”
The quake also had an effect on the Naval facility at China Lake which conducts weapons research and training, though the extent of the damage was not clear, the Post wrote:
Naval Air Weapons Station China Lake was “not mission capable until further notice,” and nonessential personnel were authorised to evacuate to the surrounding area, the base announced on Facebook without providing further details on the damage sustained.
“It was bad. Man. It hasn’t stopped yet,” Ridgecrest resident Jeremiah Jones told the Los Angeles Times.
The China Lake facility was already hit by ruptured ground following the first quake, the L.A. Times reported, when United States Geological Survey (USGS) research geophysicist Rob Graves estimated both sides of the fault involved could have slid six to eight inches past each other.
The Saturday earthquake released approximately 11 times more energy than the one on Thursday.
According to CNN, the USGS has reported nearly constant aftershocks at the rate of roughly one per minute since the magnitude 6.4 quake, with Ridgecrest Police Chief Jed McLaughlin warning reporters, “This isn’t going to stop in the near future. The aftershocks, they haven’t slowed down since the 7.1 (magnitude earthquake). For a period of time there was constant vibration.” Some 2,300 quakes have been detected in southern California since the fourth of July, though only 300 would have been noticeable.
CalTech seismologist Lucy Jones told CNN the set of quakes part of a “very energetic system” and that there was a roughly 10 per cent chance that the Searles Valley region will encounter another magnitude 7.0 earthquake.
“Today’s M7.1 has a 1 in 20 of being followed by something even bigger,” Jones told CNN. “Smaller quakes—M5s are likely and a M6 is quite possible.”
Some damage was reported in Los Angeles but was mainly limited to “localised power failures and downed wires,” according to the New York Times. Structural damage such as homes sliding off foundations and collapsed retaining walls was reported in San Bernardino County.
The quakes were far from the 1,287km San Andreas fault zone, which forms the boundary between the Pacific and North American tectonic plates and has long generated fears of an inevitable future earthquake dubbed “the Big One.” (In theory, it could hit all of Southern California at magnitude 8.2, resulting in what would almost certainly be jaw-dropping damage.)
Per the L.A. Times, the San Andreas fault’s distance of 161km away at its closest point makes it unlikely to usher in such a catastrophe—though the aftershock system from the quakes could last for years.
Scientists cannot currently predict earthquakes with any accuracy whatsoever and the USGS says it does not expect to develop that capacity within the “foreseeable future.” The best they can do at this time is estimate the likelihood that a quake will occur in a region over a specific time period.
“In California, we expect to have a magnitude 7 once every 10 to 20 years, and the last one was 20 years ago,” Jones told the L.A. Times. “Think of this as a return to what California is supposed to be doing.”
Those near the quakes are advised to secure and mount furniture such as bookcases or television sets, install locks on cabinets, use quake-resistant hooks to mount wall decorations, and survey their homes for objects that could be locked down, per the L.A. Times.
Additionally, residents should either ensure that their homes are quake-resistant (or ask their landlord to do so), have two weeks’ worth of nonperishable food, water, and medical supplies, and develop a plan for what to do in the aftermath of a quake.