What kind of plate is the san andreas fault

North of Cape Mendocino, the San Andreas fault merges with the plate boundary of the Cascadia subduction zone that lies offshore of northernmost California, Oregon, and Washington. We know from paleoseismic investigations in Washington and Oregon and tsunami records in Japan, a magnitude 9 earthquake ruptured the Cascadia subduction zone in Although many Bay Area residents remember the Loma Prieta as the "big one", it pales in comparison to these earlier fault ruptures.

Real-time Earthquakes. Indeed, almost none of the SAF's fault plane is vertical. The plates are rigid or almost rigid slabs of rock that comprise the crust and upper mantle of the Earth. The SAF is about miles long as the crow flies and about miles long when its curves are measured.

It is roughly ten miles deep, and reaches from the Salton Sea in Imperial county to Cape Mendocino in Humboldt county. The plates are continually moving but where the touch each other, they get stuck. As the rest of the plates moves, the stuck parts deform like compressing a spring so they build up stress in the rocks along the fault.

When the rock breaks or slips, the suddenly plates move, causing an earthquake. The entire process is called elastic rebound. As they break and scrape by one another, they produce seismic waves that travel through the ground and shake the surface. We know this shaking as earthquakes. While we think of plates as rigid, they can stretch a little, like pizza crust. This results in a curious effect: while the Pacific Plate is moving northwest relative to the North American Plate at an average rate of about 2.

The difference is being taken up by slip along the other parallel faults. This can be demonstrated by a deck of cards. Thrust faults can produce larger earthquakes than strike-slip faults. The fault that caused the Sumatra earthquake and tsunami in December was this sort of fault. By studying the earthquake, scientists learned that this ability of rock to stretch and store energy like a spring is what enables earthquakes to happen. Earthquakes are now explained by the elastic rebound theory, which goes something like this: Stress is applied to rock or to an existing fault over a period of time.

This usually happens at a plate boundary where two plates are moving in different directions, or in the same direction at different speeds. As the stress builds, strong rock or a locked fault a fault where the two sides are held together by friction deform elastically.

Eventually, the stress overcomes the rock's strength or the fault's friction, and either the rock fractures or the fault slips. The energy that's released sets an earthquake in motion. Or near the network of active California faults that feed into it? Keep in mind the fault is always moving about 2 inches a year.

While the San Andreas Fault Zone is the most studied in the world, nothing can prevent a major earthquake from happening.

The key to being safe during an earthquake is preparation. While an earthquake safety kit will be of help after an earthquake, nothing replaces the conversations you have with your family members before an earthquake. CEA offers earthquake home insurance premium discounts for houses and mobilehomes that have been retrofitted. Learn about the potential geologic structural threats to your home in case of a major earthquake.

The violent shaking from earthquakes can:. If your home was built before , it may also be vulnerable to serious structural damage. With safety planning, reinforcing the outside of home and your personal property, and earthquake insurance , you stand a better chance of riding out the next San Andreas rupture.

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