2.1 earthquakes can occur near faults
DESCRIPTION
2.1TRANSCRIPT
Rocks Move Along Faults
• Fault – a fracture, or break, in Earth’s lithosphere, along which blocks of rock move past each other
• As rocks in the faults bend, a lot of stress is put on them
• Stress – force exerted when an object presses on, pulls on, or pushes against another object
Rocks Move Along Faults
• The sudden release of stress causes an
earthquake: shaking of the ground caused by sudden movement of large blocks of rock along a fault
• Most faults are located along tectonic plate boundaries
• The strength of an earthquake depends on:• How much stress builds
up before the rocks move
• The distance the rocks move
80 percent of all earth-quakes occur in a belt around the edges of the Pa-cific Ocean [Pacific Rim]
Rocks Move Along Faults
• ALL earthquakes occur in the lithosphere [it is dense, solid]
• FEW earthquakes occur below the lithosphere only because the tec-tonic plates are still cold to break
Faults are classified by how rocks move
•3 main types of faults•Normal faults – pulled apart
•Reverse faults – pushed/pressed together
•Strike-slip faults – move sideways
Normal Faults
• Stress pulls rocks apart
• Common near bound-aries where tectonic plates are moving apart
• Ex. Great Rift Valley of Africa
Reverse Faults
• Block of rock above the fault plane moves up relative to the other block
• Stress presses rocks to-gether
• Faults can occur near collision-zone bound-aries
• Ex. Continental/Oceanic collision