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The city of Ukiah, in Northern California sits right next to the Maacama Fault, which is capable of M=7.5 earthquakes and poses a significant threat to the region.
In California, when most people think about faults, their thoughts are immediately drawn to the San Andreas, and to a lesser extent, the Hayward Fault. However, in Northern California, there is almost no seismicity on the San Andreas. Instead,
the majority of the earthquakes occur on faults that are parallel to and east of the San Andreas. These faults are part of the greater San Andreas system, and are capable of generating large magnitude earthquakes. Today, we thought we'd take a look at two of them.
The Maacama and Bartlett Spring faults lie approximately 50 km and 80 km east of the San Andreas respectively. All of these faults are members of the greater transform boundary between the Pacific and North American plates, a margin primarily composed of nearly pure right-lateral strike-slip faults. Both the Maacama and Bartlett Springs faults are known to be active based on seismicity and creep. Creep implies there is very slow, relatively continuous motion on a fault due to tectonic deformation.
While faults that creep tend to not rupture in large earthquakes, the Hayward Fault running through the San Francisco East Bay creeps and has ruptured in M=7+ quakes. So, it is not a black and white rule.
Comment: There could be many reasons this particular area of Antarctica is seeing greater moss growth. But it would be foolish to apply that to the entire planet. Other studies indicate the period of increased growth may be at an end.