These mud hills were once at the bottom of Lake Cahuilla in California David McNew/Getty Images
California is overdue for a major earthquake on the southern San Andreas fault, which could be due to the absence of a large lake that may have triggered past quakes.
The San Andreas fault runs through California for 1200 kilometres, forming the boundary between the Pacific and North American tectonic plates. The southern section of the fault, east of Los Angeles, has been abnormally quiet, with no large earthquakes for nearly 300 years despite an average gap …
