Chapter 13 Flashcards
(19 cards)
Aftershock
An earthquake that occurs as a consequence of a previous earthquake of larger magnitude.
Intensity Scale
A scale for estimating the intensity of a destructive geologic event, such as an earthquake or a hurricane, directly from the event’s destructive effects.
Earthquake
The violent motion of the ground that occurs when brittle rock under stress suddenly breaks along a fault.
Magnitude Scale
A scale for estimating the size of an earthquake using the logarithm of the largest ground motion registered by a seismograph or the logarithm of the area of the fault rupture.
Epicentre
The geographic point on Earth’s surface directly above the focus of an earthquake.
P Wave
The first type of seismic wave to arrive at a seismograph from the focus of an earthquake; a type of compressional wave.
Fault Slip
The distance of the displacement of the two blocks of rock on either side of a fault that occurs during an earthquake.
Recurrence Interval
The average time between large earthquakes at a particular location; according to the elastic rebound theory, the time required to accumulate the strain that will be released by fault slipping in a future earthquake.
Foreshock
A small earthquake that occurs in the vicinity of, but before, a main shock.
S Wave
The second type of seismic wave to arrive at a seismograph from the focus of an earthquake; a type of shear wave S waves cannot travel through liquids or gases.
Building Codes
A set of standards for the design and construction of new buildings that specifies the intensity of shaking a structure must be able to withstand during an earthquake.
Elastic Rebound Theory
A theory of faulting and earthquake generation holding that, as the crustal blocks on either side of a fault are deformed by tectonic forces, they remain locked in place by friction, accumulating elastic strain energy, until they fracture and rebound to their undeformed state.
Fault Mechanism
The orientation of the fault rupture and the slip direction of a fault that caused an earthquake.
Focus
The point along a fault at which slipping initiates an earthquake.
Seismic Hazard
The intensity of shaking and ground disruption by earthquakes that can be expected over the long term at some specified location.
Seismic Risk
The earthquake damage that can be expected over the long term in a specified region, usually measured in average dollar losses per year.
Seismograph
An instrument that records the seismic waves generated by earthquakes.
Surface Wave
A type of seismic wave that travels around Earth’s surface from the focus of an earthquake and arrives at a seismograph later than S waves.
Tsunami
A fast-moving sea wave, generated by an earthquake that lifts the seafloor, that propagates across the ocean and increases in size when it reaches the shore.
