Earthquake 2
secondary waves aka
S waves
The radius of the circle seismologists draw on a map is equal to the distance from a station to an earth quakes
epicenter
The magnitude of an earthquake is measured by the
Richter Scale
When the force on rocks is great enough, they break, producing vibrations called
earthquakes
An earth quake that registers 7.2 on the RIchter scale releases about ____ times as much energy as an earthquake that registers 5.2 on the scale
900
When rocks break because of stress, the energy released is in the form of an
Earthquake
Most earthquakes happen (3 reasons)
1) without warning 2)in areas where earthquakes have occurred in the past 3)along plate boundaries
The ____ is most damaging seismic wave
Love
The boundary between the upper mantle and the crust is called the
Moho discontinuity
The ___ wave travels the slowest of the seismic waves
Rayleigh
Primary and secondary wave slow down when they hit the plastic like layer of the upper mantle called the
asthenosphere
tsunamis are
caused by a underwater earthquake
The farther apart primary, secondary, and surface waves are, the ____ away the epicenter is
farther
Once the elastic limit of rocks is passed, they break and move along surfaces called
faults
The point in Earth's interior where the energy release of an earthquake occurs is the
ffocus
A person located twice as far from an epicenter of an earthquake as another person will notice that the time between the arrival of the primary and secondary waves will be
larger
Amount of energy releases is measured by
magnitude
The speed of the P-wave increases when going from a substance that is
plastic-like to solid
The ___ waves are the first to reach a seismograph after an earthquake
primary
____ waves arrive at a seismograph station first
primary
_____ waves move through the earth by causing particles of rocks to move back and forth in the same direction as the waves
primary
_____- waves move through earth by causing particles in rocks to move at right angles to the direction of the waves
secondary
paper record of a seismic event
seismograms
instruments that record seismic activity
seismographs
people who study earthquakes and seismic waves
seismologists
Primary waves ___ when they hit the liquid outer core
slow down
Seismic waves ____ when they reach the asthenosphere
slow down
Seismic waves ___ when they reach the mesosphere
speed up
Seismic waves ____ when they reach the bottom portion of the lithosphere
speed up
Secondary Waves ____ when they hit the liquid outer core
stop
Most of the destruction during an earthquake is caused by ____ waves
surface
The most destructive seismic wave are
surface waves
waves that travel outward from the epicenter
surface waves
At least ___ seismograms are needed to accurately locate an earthquake
three
True or False: Seismologists use the Richter Scale to describe the magnitude of earthquakes
true
