GEOLOGY

Detailed explanation-1: -The transform plate boundary is a broad zone forming as the Pacific Plate slides northwestward past the North American Plate. It includes many lesser faults in addition to the San Andreas Fault.

Detailed explanation-2: -The Pacific Plate (on the west) slides horizontally northwestward relative to the North American Plate (on the east), causing earthquakes along the San Andreas and associated faults. The San Andreas fault is a transform plate boundary, accomodating horizontal relative motions.

Detailed explanation-3: -The San Andreas fault line formed about 30 million years ago as the North American plate engulfed nearly all of the Farallon plate. Since then, the North American plate has ground against the Pacific plate at a boundary called a strike-slip fault.

Detailed explanation-4: -When oceanic or continental plates slide past each other in opposite directions, or move in the same direction but at different speeds, a transform fault boundary is formed. No new crust is created or subducted, and no volcanoes form, but earthquakes occur along the fault.

Detailed explanation-5: -The 1, 200-kilometer-long San Andreas fault zone is part of the boundary between the Pacific and North American plates, and thus is known as a transform fault.