# Shared Flashcard Set

## Details

Ch4
Ch4
28
Geology
02/15/2011

Term
 aftershock
Definition
 :  A series of earthquakes following the first or main shock.  They are usually of lower       magnitude than the main shock.
Term
 asperity
Definition
 Rough spot or “knot” along a fault that stops movement along that section for a period of time.       The bigger the asperity, the greater the stress buildup and the larger the earthquake that results. (See also      seismic gap.)
Term
 body wave
Definition
 Earthquake waves that travel through the body of the earth
Term
 elastic rebound theory
Definition
 The theory that movement along a fault and the resulting seismicity is the result of       an abrupt release of stored elastic strain energy between two rock masses on either side of the fault.
Term
 epicenter
Definition
 The point at the surface of earth directly above the focus of an earthquake
Term
 fault
Definition
 Fracture in the earth along which there has been displacement
Term
 fault creep (tetonic):
Definition
 The gradual slip or motion along a fault without an earthquake.
Term
 focus (pl. foci)  (hypocenter
Definition
 Point within the earth where an earthquake originates.
Term
 intensity scale
Definition
 An earthquake rating scale (I-XII) based upon subjective reports of human reactions to      ground shaking and upon the damage caused by an earthquake.
Term
 isoseismal:
Definition
 Lines on a map that enclose areas of equal earthquake shaking based upon an intensity scale.
Term
 longitudinal wave; (P-wave
Definition
 A type of seismic wave involving particle motion that is alternating  expansion and compression in the direction of wave propagation.  Also known as compressional waves,        they resemble sound waves in their motion.
Term
 magnitude (earthquake
Definition
 A measure of the strength or the strain energy released by an earthquake at its       source.  (See moment magnitude, Richter magnitude).
Term
 modified Mercalli scale
Definition
 Earthquake intensity scale from I (not felt) to XII (total destruction)based upon damage and reports of human reactions.
Term
 moment magnitude (MW or M
Definition
 A scale of seismic energy released by an earthquake based on the product of the rock rigidity along the fault the area of rupture on the fault plane, and the amount of slip.
Term
 .  paleoseismicity:
Definition
 The rock record of past earthquake events in displaced beds and liquefaction features in       trenches or natural outcrops.
Term
 .  precursor (of earthquakes
Definition
 Observable phenomena that occur before an earthquake and indicate that an       event is soon to occur.
Term
 recurrence interval
Definition
 The return period of an event, such as a flood or earthquake, of a given magnitude.       For flooding, it is the average interval of time within which a given flood will be equaled or exceeded by       the annual maximum discharge.
Term
 .  resonance
Definition
 The tendency of a system (a structure) to vibrate with maximum amplitude when the       frequency of the applied force (seismic waves) is the same as the vibrating body’s natural frequency
Term
 Richter Magnitude Scale
Definition
 The logarithm of the maximum trace amplitude of a particular seismic wave on    a seismogram, corrected for distance to epicenter and type of seismometer.  A measure of the energy     released by an earthquake.
Term
 seismic gap
Definition
 The segment along an active fault that has seismically been quiet relative to segments at   either end.  It is the part of the fault most likely to rupture and generate the next earthquake.  (See also        aperity.)
Term
 seismogram
Definition
 The recording from a seismograph.
Term
 seismograph
Definition
 An instrument used to measure and record seismic waves from earthquakes
Term
 spontaneous liquefaction
Definition
 :  Process whereby water-saturated sands, clays, or artificial fill suddenly become fluid upon shaking, as in an earthquake.
Term
 stress
Definition
 The force applied on an object per unit area, expressed in pounds per square fool (lb/ft2) or       kilograms per square meter (kg/m2).
Term
 strain
Definition
 Deformation resulting from an applied stress (= force per unit area).  It may be elastic    (recoverable) or ductile (nonreversible
Term
 transverse (shear) wave; S-wave
Definition
 A seismic wave propagated by a shearing motion that involve oscillation perpendicular to the direction of travel.  It travels only in solids.
Term
 tsunami (pl. tsunamis
Definition
 Large sea wave produced by a submarine, earthquake, a volcanic eruption, or a            landslide.  Incorrectly known as a tidal wave.
Term
 wave period (T):
Definition
 The time (in seconds) between passage of equivalent points on two consecutive waveforms.
Supporting users have an ad free experience!