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Geology 106 final
final
52
Geology
Undergraduate 1
12/14/2013

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Term
Liquefaction
Definition
process by which water-saturated, unconsolidated sediments are transformed into a substance that acts like a liquid
Term
seismic retrofit
Definition
the modification of existing structures to make them more resistant to seismic activity, ground motion, or soil failure due to earthquake
Term
resonance
Definition
the tendency of a system to oscillate with greater amplitude at some frequencies than at others
Term
attenuation
Definition
is the gradual loss in intensity of any kind of flux through a medium
Term
hydrofracture (“hydrofracking”)
Definition
the fracturing of rock by a pressurized liquid
Term
subduction zone
Definition
one convergent plate going under the other found at volcanoes, earthquakes and Mountain ranges
Term
Cascadia subduction zone
Definition
is a subduction zone, a type of convergent plate boundary that stretches from northern Vancouver Island to northern California. It is a very long sloping fault that separates the Juan de Fuca and North America plates
Term
Gorda plate
Definition
plate that neighbors juan de fuca plate and is closet to Humboldt county, it also is different then plates because it has so many deformation within the plate boundaries
Term
magnetic stripe (magnetic anomaly)
Definition
local variation in the Earth's magnetic field resulting from variations in the chemistry or magnetism of the rocks
Term
seismic waves
Definition
waves of energy that travel through the Earth's layers, and are a result of an earthquake, explosion, or a volcano that imparts low-frequency acoustic energy
Term
S wave (secondary wave, shear wave)
Definition
one of the two main types of elastic body waves, so named because they move through the body of an object, S-waves are like waves in a rope, as opposed to waves moving through a slinky, the P-wave
Term
seismogram
Definition
a graph output by a seismograph. It is a record of the ground motion at a measuring station as a function of time
Term
epicenter
Definition
he point where an earthquake or underground explosion originates
Term
Local magnitude (Richter magnitude, ML)
Definition
developed to assign a single number to quantify the energy released during an earthquake.The scale is a base-10 logarithmic scale. The magnitude is defined as the logarithm of the ratio of the amplitude of waves measured by a seismograph to an arbitrary small amplitude
Term
Intensity
Definition
the power transferred per unit area
Term
theory
Definition
an idea that is suggested or presented as possibly true but that is not known or proven to be true
Term
plastic behavior
Definition
the deformation of a material undergoing non-reversible changes of shape in response to applied forces
Term
thrust fault
Definition
type of fault, or break in the Earth's crust across which there has been relative movement, in which rocks of lower stratigraphic position are pushed up and over higher strata
Term
left-lateral strike-slip fault
Definition
type of fault, or break in the Earth's crust across which there has been relative movement, in which rocks of lower stratigraphic position are pushed up and over higher strata
Term
half-life
Definition
is the amount of time required for a quantity to fall to half its value as measured at the beginning of the time period
Term
coseismic subsidence
Definition
the dropping in sea level around seismic plates
Term
prediction
Definition
statement about the outcome of a future event
Term
Alquist-Priolo law
Definition
The Act was one of several that changed building codes and practices to improve earthquake safety. These changes are intended to reduce the damage from future earthquakes.

1) It directs the State of California Division of Mines and Geology (now known as the California Geological Survey) to compile detailed maps of the surface traces of known active faults. These maps include both the best known location where faults cut the surface and a buffer zone around the known trace(s);

2) It requires property owners (or their real estate agents) to formally and legally disclose that their property lies within the zones defined on those maps before selling the property; and

3) It prohibits new construction of houses within these zones unless a comprehensive geologic investigation shows that the fault does not pose a hazard to the proposed structure.
Term
reverse cyclic loading
Definition
tests normal and pre-stressed concrete beams for earthquake safety
Term
cross-bracing
Definition
system utilized to reinforce building structures in which diagonal supports intersect
Term
transform fault
Definition
type of fault whose relative motion is predominantly horizontal and spreads apart form the other boundaries
Term
Pacific plate
Definition
largest tectonic plate on earth
Term
theory of plate tectonics
Definition
theory that earth crust is broken up into tectonic plates that create divergent, convergent and transform faults which create volcanoes, mountain ranges and
Term
P wave
Definition
type of elastic wave, called seismic waves in seismology, that can travel through a continuum and P-wave is often said to stand either for primary wave, as it has the highest velocity and is therefore the first to be recorded; or pressure wave,[1] as it is formed from alternating compressions and rarefactions.
Term
seismograph
Definition
instruments that measure motions of the ground, including those of seismic waves generated by earthquakes, volcanic eruptions, and other seismic sources
Term
magnitude
Definition
measure of the energy of an earthquake
Term
Modified Mercalli scale
Definition
seismic scale used for measuring the intensity of an earthquake
Term
elastic rebound theory
Definition
explanation for how energy is spread during earthquakes/ rocks on opposite sides of a fault are subjected to force and shift, they accumulate energy and slowly deform until their internal strength is exceeded. At that time, a sudden movement occurs along the fault, releasing the accumulated energy, and the rocks snap back to their original undeformed shape.
Term
hanging wall
Definition
occurs above the fault plane
Term
normal fault
Definition
A fault in which the hanging wall has moved downward relative to the footwall
Term
blind thrust fault
Definition
fault plane terminates before it reaches the Earth's surface/ difficult to find until they rupture.
Term
recurrence interval
Definition
Interval between two major earthquakes
Term
ghost forest
Definition
forrest killed during earthqueake
Term
forecast
Definition
predict or estimate
Term
soft story (in a building)
Definition
multi-storey building in which one or more floors have windows, wide doors, large unobstructed commercial spaces, or other openings in places where a shear wall would normally be required for stability as a matter of earthquake engineering design
Term
Focal mechanism
Definition
describes the inelastic deformation in the source region that generates the seismic waves
Term
Juan de Fuca plate
Definition
tectonic plate generated from the Juan de Fuca Ridge and is subducting under the northerly portion of the western side of the North American Plate at the Cascadia subduction zone
Term
North American plate
Definition
tectonic plate covering most of North America, Greenland, Cuba, Bahamas, and parts of Iceland and the Azores
Term
surface wave
Definition
mechanical wave that propagates along the interface between differing media, usually two fluids with different densities
Term
focus (hypocenter, hypocentre)
Definition
refers to the site of an earthquake or a nuclear explosion
Term
Moment magnitude
Definition
used by seismologists to measure the size of earthquakes in terms of the energy released
Term
Hypothesis
Definition
a proposed explanation for a phenomenon
Term
elastic behavior
Definition
he tendency of solid materials to return to their original shape after being deformed
Term
footwall
Definition
The underlying block of a fault having an inclined fault plane.
Term
isotope
Definition
variants of a particular chemical element such that, while all isotopes of a given element have the same number of protons in each atom, they differ in neutron number
Term
tsunami
Definition
series of water waves caused by the displacement of a large volume of a body of water, generally an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater explosions (including detonations of underwater nuclear devices), landslides, glacier calvings, meteorite impacts and other disturbances above or below water all have the potential to generate a tsunami
Term
precursor
Definition
a phenomenon of wave propagation in dispersive media
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