The southern part of the San Andreas fault has been described as “locked, loaded and ready to roll.”
Director of the Southern California Earthquake Center Thomas Jordan cited the potential danger while speaking at the National Earthquake Conference in Long Beach on Wednesday.
As reported by the Los Angeles Times, the San Andreas fault is known to be the longest and potentially most dangerous fault in California. A magnitude 7.9 earthquake had struck San Andreas in 1857, affecting as many as 185 miles between Monterey County and the San Gabriel Mountains.
In his opening keynote talk, Jordan said, “The springs on the San Andreas system have been wound very, very tight. And the southern San Andreas fault, in particular, looks like it’s locked, loaded and ready to go.”
What poses an issue is that, southeast of the Cajon Pass in San Bernardino County, for example, the fault has remained unmoved since an earthquake in 1812. Moreover, southeast towards the Salton Sea, the fault has not moved since 1680 or 1690.
FOX LA noted that an earthquake with magnitude 7.8 could cause as many as 1,800 deaths and an alarming number of 50,000 injuries. Simulations of the earthquake – occurring on the fault, beginning at the Salton Sea and stretching west toward the San Gabriel mountains – reveal that seismic waves “bent into the Los Angeles area,” according to Jordan.
“You can see that this area of influence by the shaking has now expanded out to huge proportions,” Jordan said. “You see that big directivity pulse out in front, as that energy is being shoved down that fault, that directivity pulse leads energy into seismic waves that excite the sedimentary basins, like the San Fernando Valley and the Los Angeles Basin,” and through San Bernardino, Jordan said. “You’ll notice large shaking in the Los Angeles region persisting for long periods of time.”
Jordan expressed his concern over the significant lack of movement along the fault, saying that the tectonic plates have not been relieving stress.
“Were the Fort Tejon shock to happen today,” the Southern California Earthquake Data Center wrote, “the damage would easily run into billions of dollars, and the loss of life would likely be substantial, as the present day communities of Wrightwood, Palmdale, Frazier Park, and Taft (among others) all lie upon or near the 1857 rupture area.”