Easter 2010 Earthquake Revealed New Fault Along Salton Sea
Researchers who have been studying the aftermath of the Easter Sunday earthquake of 2010 announced a new fault line has been discovered as a result of the 7.2 temblor.
The earthquake, centered in Mexicali, hit in the afternoon hours on Easter, and was felt through the Palm Springs area and into the Los Angeles and San Diego areas.
Seismic researchers said the April 4 event triggered surface movement on several Southern California faults, including a new one near the Salton Sea.
“Every earthquake is an opportunity for new understanding, but few in recent times have created more distinct new information than the April 4, 2010 Baja quake,” said USGS Director Marcia McNutt. “Seismologists and geologists are eager to use the triggered fault movement for unraveling complex stress interactions in the plate boundary region of the Imperial Valley.”
Of the few dozen faults in the Coachella and Imperial valleys that showed surface movement, only about half were previously known to researchers or mapped.
Of the known faults, the newly observed movement revealed one major fault to be longer than previously known, and another was confirmed to be active.
The newly-named Ocotillo Fault, near the town of Ocotillo, was known and suspected to be active, researchers said. The triggered movement — which shifted 3 inches in both directions– confirms it is an active fault.
The Elsinore Fault, one of three major northwest-trending faults in this part of Southern California, showed triggered movement extending three kilometers (almost 2 miles) to the southeast beyond its previously known extent.
“It was exciting to identify and map an extensive and complex zone of largely unmapped faults in the Yuha Desert area of California’s southern border with Mexico,” said CGS geologist Jerry Treiman, adding: “These faults may play a significant role in distributing strain to other major faults in the Salton Trough.”
Locating and carefully mapping the small surface movements was made more thorough by NASA’s high-tech Uninhabited Aerial Vehicle Synthetic-Aperture Radar (UAVSAR) in concert with traditional field geology methods of traversing almost 200 square miles of terrain on foot, and measuring small gaps and cracks in the ground with fault offsets of only a few millimeters.
The previously unknown Yuha Fault displayed some of the largest movements detected, between 50-60 mm (about 2 to 2.5 inches). Displacements in the Brawley Fault Zone, although not as large as movement on the Yuha Fault, were large enough to damage concrete-lined irrigation canals.
