Final answer:
The San Andreas Fault is a transform fault at the boundary of the Pacific Plate and the North American Plate, causing significant geological movement and leading to major earthquakes in California.
Step-by-step explanation:
The San Andreas Fault is a prominent geological feature in California, renowned for its role in the state's earthquake activity. It is a transform fault where the Pacific Plate and the North American Plate slide past each other. This fault extends approximately 600 miles from the Gulf of California to the area northwest of San Francisco.
Los Angeles, located on the Pacific Plate, is moving northward due to the fault's activity, with an average velocity of about 6 cm per year. Over several million years, this motion could result in Los Angeles becoming an island near San Francisco. The fault's movement is also responsible for significant earthquakes, such as those near Parkfield that occur roughly every 25 years, moving about 1 meter with each slip. The Los Angeles region has a longer interval between major earthquakes, approximately every 150 years, with an average motion of about 7 meters.
The constant build-up of tension along the San Andreas Fault suggests imminent seismic activity. Sensitive instruments monitor this tension by measuring how the ground is distorting and contracting beneath the surface. Understanding the movements of the San Andreas Fault is crucial for earthquake preparedness and urban planning in California.