New type of weak temblors in upper mantle detected
Mysterious earthquakes rattle deep beneath Southern California.
The tiny quakes originate from tens of kilometers below ground along the Newport-Inglewood Fault near Long Beach, Calif., seismologists report in the Oct. 7 Science. Rocks at that depth should be too hot and malleable to snag and break — a key mechanism behind earthquakes. Some unknown process must be at play in the roots of the fault that makes this new type of earthquake possible, says study coauthor Asaf Inbal, a seismologist at Caltech.
“This is a wide open question that we don’t have a good answer to,” he says.
The quakes puzzle scientists, but they don’t pose a direct threat, says Yuri Fialko, a geophysicist at the Scripps Institution of Oceanography in La Jolla, Calif. “Luckily for us, they remain small and don’t grow into bigger, potentially damaging events,”