Geology Final Exam

What is an earthquake?
Click the card to flip 👆
1 / 28
Terms in this set (28)
What is an earthquake?
sudden movement of earths lithosphere
A focus
point underground where rock first ruptures (hypocenter)
Epicenter
The point on the Earth's surface located directly above the focus of an earthquake.
Brittle Rocks
have a small to large region of elastic behavior, but only a small region of ductile behavior before they fracture.
Ductile Rocks
have a small region of elastic behavior and a large region of ductile behavior before they fracture.
Seismology
The field also includes studies of earthquake environmental effects such as tsunamis as well as diverse seismic sources such as volcanic, tectonic, oceanic, atmospheric, and artificial processes such as explosions.
Seismograph
any of various instruments for measuring and recording the vibrations of earthquakes
What are the different types of earthquake waves?
P (primary) waves: shake the ground in the direction they are propagating. Compressional which means they move through a solid or liquid by pushing or pulling similar to the way sound travels through the air.

S (secondary) waves: shake the ground in perpendicular to the direction they are propagating

surface waves
How can seismic waves be used to calculate distance to an epicenter and ultimately the location of the earthquake
Seismogram
Amplitude
height (on paper) of the strongest wave.
love wavesare surface seismic waves that cause horizontal shifting of the Earth during an earthquake.rayleigh wavesan undulating wave that travels over the surface of a solid, especially of the ground in an earthquake, with a speed independent of wavelength, the motion of the particles being in ellipsesWhere do most earthquakes occur, and why?Pacific seismic belt, is found along the rim of the Pacific Ocean. B/c its region of young, growing mountains and deep ocean trenches which invariably has parallel mountain chainsHow do you determine the epicenter location of an earthquakeMeasure the distance between the first P wave and the first S waveForeshocksa mild tremor preceding the violent shaking movement of an earthquakeAftershocksa smaller earthquake following the main shock of a large earthquakeWhat is the Wadatti-Benioff zone? Where is it?planar zone of seismicity corresponding with the down-going slab in a subduction zone. beneath volcanic island arcs and continental margins above active subduction zonesWhat does the Wadattizone tell us about plate tectonics?They can be produced by slip along the subduction thrust fault or slip on faults within the downgoing plate, as a result of bending and extension as the plate is pulled into the mantle.What factors (physical and cultural factors) influence the amount of destruction produced by an earthquake?location magnitude depth distance from epicenter geologic conditions architectureWhat is the Mercalli scale, how is it established, and for what is it used?developed by the Italian volcanologist Giuseppe Mercalli in 1884 and expanded to include 12 degrees of intensity in 1902 by Adolfo Cancani. measuring the intensity of an earthquakeHow are Mercalli values plotted on a map? What can they tell us about underlying geologydescriptions and observations are then assigned the appropriate intensity by consulting the detailed description of the Modified Mercalli Scale. a geographic representation of the distribution of ground shakingRichter scale and for what is it used?to rate the magnitude of an earthquake, that is the amount of energy released during an earthquakeWhat maps are produced to help geologists and others understand the risk/potential for damage from earthquakes?National seismic hazard mapsWhat are some of the major concerns for intensification of earthquakes in some areas due to other geologic factors?liquefaction tsunamis ground motion social and physical damage fires landslides ground displacementWhy are some areas prone to earthquake damage while nearby areas are notmost of the seismic activity is experienced on or near the plate margins that make up the crust of the earth surface. This is due to the high activity at these points where new material is 'created' or 'destroyed'.What is meant by amplification/acceleration of ground movement and how does it cause liquefaction?Seismic waves travel differently through different rock materials/ they may have more of an effect on something built on clay rather then graniteWhat is a tsunami and how are they generated?displacement of the seafloor in turn displaces a large volume of water about it. The sudden displacement causes waves to disperse in all direction.Why are waves more significant near the coast rather than out at sea?As a wave approaches the shore it slows down from drag on the bottom when water depth is less than half the wavelength