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Cajon Pass may allow an earthquake to occur along two fault lines simultaneously. | Credit: Illustration by Julia Wytrazek \/ Getty Images<\/p>\n
California is tense, or at least its fault lines are. The southern part of the state is at risk of experiencing a devastating earthquake as stress levels along both the San Andreas and San Jacinto faults are at a peak. While researchers cannot predict when the earthquake will occur, understanding the state of these two fault lines and their associated risks can help to better prepare civilians and municipalities.<\/p>\n
Tension at the gate<\/p>\n
Stress levels along the San Andreas and San Jacinto fault lines<\/a> have \u201cnow reached high levels,\u201d and the \u201ctwo fault systems may interact when their stress levels become similar,\u201d leading to a massive earthquake, said a study published in the journal JGR: Solid Earth<\/a>. After analyzing 1,000 years of paleoseismic data, researchers found that \u201cstress along multiple portions of the faults is the highest it has been in at least a millennium,\u201d said The Washington Post<\/a>.<\/p>\n Earthquakes<\/a> occur when a slip along a fault line \u201creleases energy built up over time,\u201d said CNN<\/a>. Stress \u201caccumulates as tectonic forces move the crust, but parts of the fault are locked and unable to slip freely.\u201d<\/p>\n While the Los Angeles area has seen its share of small earthquakes over the years, its last devastating quake was in 1857. The \u201cviolent magnitude-7.9 tremor ruptured a 225-mile stretch on the southern part of the San Andreas fault,\u201d said the Post. Since then, that portion of the fault has \u201cremained largely dormant, with stress continuing to build elsewhere along the fault, as well as along the neighboring San Jacinto fault.\u201d<\/p>\n The two fault lines meet at a point called the Cajon Pass that could serve as an \u201cearthquake gate.\u201d A gate can \u201ceither stop or transmit large ruptures between the two faults,\u201d said CNN.<\/p>\n \u201cThe conditions that determine whether the earthquake gate at Cajon Pass opens or stays closed appear to be related to how closely the stress levels on the two fault systems are aligned with each other at the time of rupture,\u201d said lead study author Liliane Burkhard in a news release<\/a>. \u201cRight now, with stress at historically high levels across the region and more than 160 years elapsed since the last major rupture, the system is in a critically loaded state.\u201d<\/p>\n Magnitude prediction<\/p>\n Because of the comparable stress levels, the Cajon Pass could \u201cfacilitate a joint rupture of both the San Andreas and San Jacinto faults simultaneously \u2014 a scenario that could be significantly more damaging than a single-fault event,\u201d said the release. The resulting quake would affect \u201cdensely populated areas including Los Angeles, San Bernardino, Riverside and the Coachella Valley.\u201d Researchers predict the tremor would be between a 7.4 and 7.8 in magnitude and cause significant damage to \u201ccritical infrastructure such as major highways, railways and energy corridors over several cities simultaneously,\u201d said CNN.<\/p>\n Major earthquakes have occurred in other parts of California<\/a>. There was a devastating 7.9-magnitude earthquake along the San Andreas fault in 1906 that affected San Francisco and the Bay Area. However, earthquakes in \u201cone part of the fault network do not relieve pressure elsewhere,\u201d said the BBC<\/a>.<\/p>\n This research does not predict when the next giant earthquake will happen, but it does \u201cimprove our understanding of earthquake interactions in Southern California,\u201d said the study. And knowing the risk can \u201chelp refine regional hazard assessments.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"When you buy through links on our articles, Future and its syndication partners may earn a commission. 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