LOS ANGELES – There is growing concern among seismologists that the 7.2 earthquake in Mexicali, Mexico, on April 4 placed more pressure on Southern California’s faults, resulting in increased quake activity over the last three months.
The latest evidence was Wednesday’s magnitude 5.4 earthquake that rolled from the mountains south of Palm Springs, leaving no major damage but rattling nerves throughout the region.
Wednesday’s quake was centered in the San Jacinto fault zone – Southern California’s most active – which runs 100 miles from the border northwesterly toward Riverside and San Bernardino.
Scientists had warned for some time that the Mexicali quake had transferred pressure from the Mexican border area toward the San Jacinto fault and nearby Elsinore fault – which runs 110 miles and could cause major damage in urban areas – making quakes there more likely.
“The probability of a larger earthquake on those faults could be high within the next year or two,” said John Rundle, a physics and geology professor at the University of California, Davis.
Experts are particularly concerned because the northern edges of the Elsinore and San Jacinto fault zones line up, respectively, near the Whittier fault, which runs into Orange and Los Angeles counties, and the San Andreas fault. Both faults could produce catastrophic quakes.