the san andreas fault runs in a northwestern direction.
the san andreas fault runs in a northwestern direction.
how far south does the san andreas fault run?
a northwestern direction
an earthquake is caused by a sudden slip on a fault. tectonic plates are always slowly moving, but they can get stuck at their edges due to friction. when the stress on the edge of a tectonic plate overcomes the friction, there is an earthquake that releases energy in waves that travel through the earth's crust and cause the shaking that is felt. for example, in california, there are two plates, the pacific plate and the north american plate. the pacific plate consists of most of the pacific ocean floor, and also includes baja california and the california coastline. the north american plate comprises most of the north american continent, including the inland parts of california, as well as parts of the atlantic and arctic oceans' floors. the primary boundary between these two plates is the san andreas fault. the san andreas fault is more than 800 miles long and extends to depths of at least 10 miles. many other smaller faults like the hayward (san francisco bay area) and the san jacinto (southern california) join with the san andreas to form the san andreas fault zone. the pacific plate grinds northwestward past the north american plate at a rate of about two inches per year.
earthquake weather
the history of earthquake investigations in california has been largely focused on the san andreas fault system, due to its strong influence in the state as the boundary between the pacific plate and the north american plate; it is the most studied fault on earth. andrew lawson, a geologist from the university of california, berkeley, had named the fault after the san andreas lake (prior to the occurrence of the 1906 san francisco earthquake) and later led an investigation into that event. the san andreas fault ruptured for a length of during the 1906 shock, both to the north of san francisco and to the south in the santa cruz mountains region. several long term forecasts for a large shock along the san andreas fault in that area had been made public prior to 1989 (the event and its aftershocks occurred within a recognized seismic gap) but the earthquake that transpired was not what had been anticipated. the 1989 loma prieta event originated on an undiscovered oblique-slip reverse fault that is located adjacent to the san andreas fault.
1989 loma prieta earthquake