Porterville is subject to earthquakes due to its location within the Pacific Ring of Fire . The geologic instability involves numerous faults , which cause many earthquakes every year , but most are of low intensity and are not felt . The primary plate boundary is the San Andreas Fault , which was the source of the 1857 Fort Tejon earthquake . Another major event that affected the Porterville area was the Kern County sequence of shocks that occurred on the White Wolf Fault during July and August 1952 . Most parts of the city are also vulnerable to floods . The San Joaquin Valley and metropolitan areas are also at risk from blind thrust earthquakes
Kern County sequence of shocks
1952 Kern County earthquake
Porterville, California