At least one earthquake happens every three minutes across Southern California.
April 27th, 2019“…….When they started their research, the earthquake catalog for the region of Southern California they studied listed 181,000 temblors recorded between 2008 and 2017. After wading through the data and scanning it through high-power computers, that number was increased to 1.8 million.
The nearly 2 million “new” earthquakes range in magnitude from negative 2.0 to 1.7……”
| Satellite image of southern California showing superposed fault lines (image sources: (1) faults from Jennings, 1994; (2) Landsat image from Jet Propulsion Laboratory of the California Institute of Technology). [Jennings, C.W., 1994, Fault activity map of California and adjacent areas: California Division of Mines and Geology, California Geologic Data Map Series, Map No. 6, scale 1:750,000. ] |
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| Oblique aerial photograph of the trace of a fault on the desert floor of southern California; view looking east at the Coachella Valley trace of the Banning Fault in the northern Coachella Valley. The linear trace on the desert floor occurs where a fault plane that is vertical in the subsurface intersects the land surface. Thus, a cross-sectional view of a fault in a road cut expresses translates into a trace on the ground surface when viewed from above in this photograph. The linear is formed by scarps (topographic expression of fault movement), by vegetation concentrated along the fault trace where ground-water ponds up-slope from the fault, and by sand dunes that form where wind-blown sand is trapped by the vegetation. Photo by J.C. Matti, USGS, December, 1979. |
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Diagram illustrating the plate-tectonic setting of southern California (image source: USGS general-interest publication “This dynamic earth: the story of plate tectonics” (Kious and Tilling, 1996). |