BERKELEY, Calif., Dec. 24 (UPI) -- The tug of the sun and the moon are causing tremors nearly 15 miles below the surface of the San Andreas fault, scientists in California said.
The tremors are occurring in fluid-lubricated ground that has the consistency of peanut butter, scientists at the University of California, Berkeley, said in a release Wednesday.
Tides raised in the Earth by the faint tug of the sun and moon are not known to trigger earthquakes directly. The tides, however, can trigger swarms of deep tremors that could increase the likelihood of quakes on the fault above the tremor zone, said university seismologist Robert Nadeau.
"The deep San Andreas Fault is moving faster when tremors are more active, presumably stressing the seismogenic zone, loading the fault a little bit faster," Nadeau said. "And that may have a relationship to stimulating earthquake activity."
