One of nature’s deep seated secrets has set down echoing all the way from California. Researchers at Stripps Institution of Oceanography, UC San Diego, the U.S. Geological Survey (USGS) and the University of Nevada, Reno, have uncovered that Southern California’s Salton Sea, may play an essential role in the earthquake process of the southern San Andreas Fault and has seemingly accelerated major earthquakes in the past.
The researchers discovered new faults in the Salton Sea besides the southern end of the San Andreas Fault. By observing displacement indicators stored in pure sedimentary deposits, the team restructured and began to explore earthquake histories. They apparently stumbled upon evidence which showed that flooding of the ancient Salton Sea and fault rupture coincided with each other’s timing. The cracking of newly found ‘stepover’ faults has the ability to hasten enormous earthquakes on the southern San Andreas Fault.
The Salton Sea encloses a geographical border at the southern tip of the San Andreas Fault where it takes a southwestward move to the Imperial Fault. The area is carefully scrutinized since the previous earthquake in this part took place around 300 years ago and the fault is assumed to have already surpassed the due date for another. The Colorado River fed the Salton Sea which was then a large natural lake.
By a procedure of imaging below the aforesaid sea, the study deemed to capture the outlining aspect of stepover faults that proceed at an angle to the San Andreas Fault. The smaller faults seemed to frequently crack and at certain instances this was consistent with the Colorado River flooding of the Salton trough. Reportedly, though the research doesn’t seem to find a potential predictability of a quake, it does trigger a readiness for a large quake that seems to follow those of smaller magnitude in the stepover region.
“To fully understand the hazards and rupture scenarios associated with the southern San Andreas Fault, we can’t limit our study to the San Andreas Fault itself. These stepover zones really need to be considered when assessing earthquake hazards and need to be examined as potential triggers for destructive earthquakes on the larger faults,” remarked Brothers, a researcher now at the USGS who conducted most of the research while a graduate student at Scripps.
The sediments gathered over several millennia on the lake floor were examined, and found that they were in concert with many flooding incidents and cracks of stepover faults which may subsequently load the San Andreas. Stress models presented that substantially normal faults with vertical displacement in the Salton Sea are more reactive to abrupt rises in vertical loads produced by filling of lake. These conditions may have apparently hastened the motion of California’s principal fault in several incidents.
However the sequence of events was not the same since the lake assumed its current dimensions. According to researchers, if the earthquake moves from south to north, the shaking of huge areas such as riverside and Los Angeles will be substantially large. Huge earthquakes on the southern San Andreas are likely to come along the liquefaction in the Imperial Valley.
The research is believed to guide the development of the Salton Sea zone. It appears in the online version of the journal Nature Geoscience on June 26.