A major earthquake – the Big One – is statistically almost certain in California in the coming decades.
According to a new study, it is likely to be followed by a series of similar-sized temblors!
The current relatively quiet seismic period – in which “far less” energy is being released in earthquakes than it is being stored from tectonic plate motions “cannot last forever.”
Moreover, the earthquake could spark a super cycle, meaning a flurry of other Big Ones, as stresses related to the original San Andreas fault earthquake are redistributed on other faults throughout Southern California.
While there would not be a literal cannonade of destruction, the earthquakes could come just decades apart, like, for example, the 7.5 major quake in 1812 on the San Andreas fault, followed by a 7.7 in 1857.
Moreover, new look at the Garlock fault shows that a cluster of four earthquakes during the late Holocene, about 500 to 2000 years ago, occurred at a time when the average slip rate on the fault was twice as fast as the long-term average slip rate.
Previous paleoseismic results show, however, that this cluster was preceded by a 3000-year lull of very small or no slip. This “on-off” behavior of the Garlock indicates that the fault may go through “super-cycles” of strain, where the strength of the fault waxes and wanes over thousands of years.
Overall, the earthquake cycles in the area may be caused by this type of super-cycle influencing the strength of many different faults in the region, including the San Andreas, Garlock and the Eastern California Shear Zone faults.
In other words, the Big One, will be something much bigger!