Chapter 12 Flashcards
movement or trembling of the ground that is caused by a sudden release of energy when rocks along a fault move
earthquake
the sudden return of elastically deformed rock to its undeformed shape
elastic rebound
location along the fault at which the first motion of an earthquake occurs
focus
90% of continental earthquakes; most damaging earthquake
shallow foci
shallow foci
0-70 km
intermediate foci
70-300 km
deep foci
300-650 km
usually by subduction zones
deep foci
the point on the Earth’s surface directly above the focus
epicenter
vibrations produced as energy is released by rocks as they slip into a new position
seismic waves
waves that travel through the body of a medium
body waves
waves that travel along the surface of a body rather than through the middle
surface waves
fastest waves
P waves
body waves that can travel through solids, liquids or gasses
P waves
second fastest waves
S waves
body waves that can only travel through solids
S waves
primary/ compression waves
P waves
secondary/ shear waves
S waves
waves that cause the most damage
surface waves
form from the conversion of energy when P and S waves reach Earth’s surface
surface waves
slowest-moving waves
surface waves
cause rocks to move side to side and perpendicular to the direction in which the waves are traveling
love waves
cause rooks to move in an elliptical, rolling motion
rayleigh waves
___ was a ___ scientist who discovered the boundary between the crust and the mantle in ___.
Andrija Mohorovicic
Croatian
1909
What are the three compositional layers of the Earth? (from outside to inside)
crust, mantle, core
What are the five mechanical layers of the Earth? (from outside to inside)
lithosphere, asthenosphere, mesosphere, outer core, inner core
locations on Earth’s surface where no body waves from a particular earthquake can be detected
shadow zones
___ waves can’t travel through Earth’s ___ which creates shadow zones.
S
liquid outer core
earthquakes occur as the overriding plate scrapes against the top of the subvergent plate (tectonic plate environment)
convergent oceanic environments
spreading motion at the mid-ocean ridge causes earthquakes (tectonic plate environment)
divergent oceanic environments
as ___ plates converge, diverge, or slide past each other horizontally rocks undergo stress; stress causes mountains to form and earthquakes to occur (tectonic plate environment)
continental
continental environments
regions of numerous, closely spaced faults
fault zones
the study of earthquakes
seismology
one who studies earthquakes
seismologist
instrument that detects and records vibrations in the ground
seismograph
tracing of earthquake motion that is recorded by an instrument
seismogram
How do scientists determine the location of the epicenter?
they triangulate the epicenter with at least three seismograph stations
measure of the strength of an earthquake
magnitude
measures magnitude based on ground motion
Richter scale
measures magnitude; preferred by scientists
moment magnitude scale
What does the moment magnitude scale base its measurements on?
strength, size of the area of the fault that moves, average distance fault block moves, rigidity of the rocks in the fault zone
the measure of the amount of damage caused by an earthquake
intensity
What measures intensity? How?
Modified Mercalli scale
with Roman numerals I-XII
What is the number one cause of injuries in earthquakes?
the collapse of buildings and other structures
giant ocean wave formed after a volcanic eruption, submarine earthquake, or submarine landslide
tsunamis
What is the most important thing to do ruing an earthquake?
stay calm
How do scientists predict earthquakes?
currently there is no reliable way of predicting exactly when and where earthquakes will occur
an area along a fault where relatively few earthquakes have occurred recently but where strong earthquakes occurred in the past
seismic gap
little earthquakes that precede earthquakes by a few seconds or weeks
foreshocks
Scientists attempt to predict earthquakes by changes in rock such as ___. Sometimes ___ can indicate earthquakes.
tilting of rock, magnetic & electrical changes in rock detected by water put in cracks
natural gas seepage
