glg111-4 - GLG111 Pages 330-363 Earthquakes and Earths...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
GLG111 Pages 330-363 Earthquakes and Earth’s Interior World’s strongest earthquake in 40 years struck Indonesia on December 26, 2004. It was a magnitude 9 earthquake. It occurred beneath the ocean, where the Eurasian plate was thrust over the Indian-Australian plate. It caused a tsunami - a massive wave- that was 500 mph. What is an earthquake? An earthquake occurs when energy stored in rocks is suddenly released. Most earthquakes are produced when stress builds up along a fault and causes the fault to slip. Mechanical energy is released which some is released through seismic waves. Hypocenter or Focus is where earthquake is generated. Epicenter is the point on Earth’s surface directly about where the earthquake occurs. Normal Faults: (outward) rocks above the fault move down with respect to the rocks below the fault. The crust is stretched horizontally, so earthquakes related to normal faults are most common along divergent plate boundaries, such as oceanic spreading centers, and in continental rifts. Reverse and Thrust Faults (inward) Many large earthquake are generated along reverse faults, especially the gently dipping variety called thrust faults. Hanging wall moves up with respect to the footwall. Such faults are formed by compressional forces such as those associated with subduction zones and continental collisions. Strike-Slip Faults (passed) Two sides of the fault slip horizontally past each other. This can generate large earthquakes. The largest strike-slip faults are transform plate boundaries, like the San Andreas fault in California and parts of the seismically dangerous Alipine fault. Volcanoes generate seismic waves and cause the ground to shake through several processes. It can transmit seismic waves . It can cause faults by the tremendous weight of the crust. Landslides cause ground shaking. Lava flows forming new crust on the Big Island of Hawaii can become unstable and suddenly collapse into the ocean.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Meteoroid Impacts occurred 200 million years ago and would have resulted in an earthquake much larger than any recorded in history. Explosions Mine blasts and nuclear explosions compress Earth’s surface, producing seismic waves. Seismic waves generated by a blast are more abrupt than those caused by a natural earthquake. How Does Faulting Cause Earthquake? Pre-Slip: An active slip fault has been offsetting a stream bed for hundreds of thousands of years, causing the stream to bend. The strike-slip is present at depth, but not obvious at the surface because it is beneath the stream or covered with loose rocks, sand and soil. Stress Increase an Elastic Strain: Tectonic stress continues to act upon the rocks along the fault. The rocks strain and flex, as shown by a slight warp in the block. The cement bridge forms a few cracks. The rocks deform elastically, changing shape slightly without breaking.
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page1 / 7

glg111-4 - GLG111 Pages 330-363 Earthquakes and Earths...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online