San Diego lies directly on one of California’s most active
fault line. The Rose Canyon Fault Line is said to be San Diego’s largest threat
in terms of a large earthquake. If this were to occur thousands to millions of
people would lose their belongings, homes, and possibly their lives. This fault
line occurs from movement of two plates sliding and grinding past each other,
also know as a transform plate movement.
Image from: http://mvsdperiod4.wikispaces.com/Transform+Boundaries
The large amount of pressure that the two plates passing by
one another create is what causes broken ground. In addition, this pressure
along with heat from inside the Earth can create metamorphic rock. Over time
this metamorphic rock surfaces due to shifting plates.
Image from: http://dnowlan.ca/VM/science7/planetearth/rocks.htm
When the plates begin to shift, during an earthquake, the
movement of the sediments causes liquefaction, the process where the soil
begins to act as a liquid in response to a change in applied stress. This
liquefaction could also create problems for the people in the area because this
will cause their houses to sink.
Image from: http://cce.oregonstate.edu/geotech/research.html
The tectonic pressure and faulting cause San Diego counties
coastal mountains that occur around the San Andreas Fault system. The fault is
a right lateral strike slip fault, which causes the mountains. An example of
these transverse ranges would be the La Jolla canyon in San Diego County.
Image from:http://membercentral.aaas.org/multimedia/galleries/field-trip-san-diego-coastal-geology-and-hazards
Sources:
http://www.eeri.org/cds_publications/earthquake_basics_series/LIQ1.pdf
http://aese2006.geology-guy.com/sd_geology_marshall.htm
http://www.ce.washington.edu/~liquefaction/html/what/what1.html
