This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
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Some California residents are all shook up after a moderate 5.8-magnitude earthquake struck about 150 miles west of Eureka on Friday, and a handful of minor quakes rattled interior Southern California over the weekend. There were no reports of injuries or damage.
The first tremblor hit off the Pacific coast at 5:42 a.m. local time (8:42 a.m. Eastern), according to the U.S. Geological Survey (USGS). Two magnitude-4.1 quakes struck north of Trona, Calif., yesterday and Saturday, the USGS said. Seven smaller quakes ranging from magnitude 3.0 to 3.3 hit before and after those shakeups.
The earthquakes serve as a reminder to Californians that their state sits on fault lines. Much more rare: a spate of minor earthquakes in central Arkansas last month that now has seismologists wondering if bigger ones are to come, the Associated Press reports.
Five quakes ranging in magnitude from 2.2 to 2.7 struck the area in November, prompting seismologists to plan to install three seismographs around Magnet Cove, where one of the temblors occurred, to determine whether they were hydrothermal quakes (from super-hot fluid under Earth’s surface that causes rocks there to move), or stemmed from an undiscovered fault, the AP says. If it’s the latter, more quakes could strike the area, which doesn’t typically experience them.
"It is abnormal. It is significant," Haydar Al-Shukri, director of the Arkansas Earthquake Center at the University of Arkansas at Little Rock, told AP. "We need to carefully watch this activity."
For more on earthquakes, including how they’re predicted and measured, see our in-depth report.
Image of seismograph machine by iStockphoto/James Benet
