GEOL 1001 Chapter : Earthquakes
Document Summary
Earth shaking caused by a rapid release of energy. ---due to tectonic stresses that cause rocks to break. ---energy moves out ward as an expanding sphere of waves. ---this waveform energy can be measured around the globe. California san andres fault has many earthquakes every week due to tectonic moving. Hawaii also due to magma under the surface. Hypocenter (or focus) - the spot within the earth where earthquakes waves originate. Causes: elastic rebound theory: relative motion between fault blocks causes rock to deform slightly (elastic strain, continued stress will cause growth of cracks, eventually, cracks grow to the point of failure. When to the rock breaks, elastic strain transform into brittle deformation, releasing earthquake energy. Stress builds until it exceeds rocks strength (stress gradually builds until the faults slips, releasing the stress suddenly and causing an earthquake. In reality it is very hard to predict earthquakes, because stress may build more quickly or less quickly over time.
