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Chapter 8 Earthquakes
Earth/Space Science
54
Science
8th Grade
11/21/2011

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Term
Earthquake
Definition

vibration of Earth

produced by the rapid release of energy

Term
Focus
Definition
Place wher waves are released from.
"point" of earthquake
Term
Faults
Definition
break in rock where movement has occured
Term
Where do Earthquakes usually happen?
Definition
along fault lines
Term
What is the name of the fault in CA? Describe it.
Definition
San Andreas Fault. it is several large faults and many fractures
Term
How do rocks behave when it is under stress?
Definition
it bends, storing elastic energy
Term
What is placing strain on the rocks?
Definition
slippage
Term
What builds up in the rock?
Definition
energy
Term
Elastic Rebound
Definition
"spring back" of a rock
Term
foreshocks
Definition
small earthquake before a major one
Term
afterschocks
Definition
small earthquake after a major one
Term
How strong are aftershocks? Can they cause damage?
Definition
1. much weaker than the main earthquake 2. yes, because building are already weak
Term
Why do scientists monitor foreshocks?
Definition
To predict/plan for future earthquakes
Term
What are 2 zones with alot of earthquake activity?
Definition
1. subduction zones 2. ocean ridges
Term
Intensity
Definition
meausure of earthquake shaking
Term
magnitude
Definition
amount of energy released at the source of an earthquake
Term
Modified Mercali Scale
Definition
estimates strength of earthquake. based on severity of ground shaking, population, building design
Term
Richter Scale
Definition
estimates the relative size of the earthquake. based on seismic waves. uses seismograph
Term
1. How many times increase in Wave Amplitude is the earthwuake per increase in number? 2. How much increase is Energy is each unit.
Definition
1. 10x in amplitude 2. 32x in energy
Term
MomentMagnitude
Definition
more precise way to meausure earthqueaks. calculated using amplitude and other factors. (more precise)
Term
How does ground shaking move?
Definition
the energy released by an earthquake travels along the surface
Term
What factors affect damage?
Definition
1. intensity 2. where the structure is built 3. duration of vibrations 4. design of structure
Term
What kind of ground material causes the most damage?
Definition
loose sediment/sand
Term
Liquefication
Definition
to make the ground fluid
Term
Tsunami. What causes one? what is the first warning?
Definition
large destructive waves. caused by vertical displacement on an ocea floor fault. first warning is rapid water withdrawl.
Term
fault creep
Definition
slow, gradual displacement
Term
stick slip motion
Definition
locked behavior followed by slippage
Term
seismograph
Definition
instument that records seismic waves
Term
seismogram
Definition
info collected from a seismograph
Term
How does a seismograph work?
Definition
there is a stick attached to bedrock. hanging from the stick is a rock & pen. When the ground moves, the rock moves the pen and it records motions.
Term
epicenter
Definition
the location on the surface directly above the focus/center of earthquake
Term
How does the interval between P and S waves reflect the distance to the epicenter?
Definition
greater the distance between the P and S wave = greater the distance to the epicenter
Term
Surface Waves
Definition
travels through outer layer. moves up, down and side to side. arrives 3rd
Term
Body Wave- Primary (P Wave)
Definition
travels theough interior. slinky waves. Moves through everything. arrives 1st
Term
Body Wave- Secondary (S Wave)
Definition
travels through interior. transverse wave motion. moves through solids only. arrives 2nd.
Term
How do you locate the epicenter on an earthquake?
Definition
  1. seismogram- look at P & S waves and determine the time difference between them
  2. look at time travel graph to determine distance between station and earthquake
  3. need 3 stations
  4. find distances from stations A B and C
  5. draw circles (with proper radius) around each station
  6. find the point where they all meet.
Term
How many stations do you need to locate the direction of an epicenter?
Definition
3 stations
Term
Is there a relationship between earthquakes and plate boundaries?
Definition
earthquakes happen more by plate boundaries
Term
Why do fires erupt after earthquakes?
Definition
pipes and electrical wires are damaged
Term
To be accepted, what do short range predictions require?
Definition
to be reliable and accurate
Term
what is the time frame for a long range forecast? Why are they useful?
Definition
30-100 years or more. useful: so you can prepare
Term
How deep can one dig into earths interior?
Definition
8 miles. 1/500th of the way
Term
What is used as "x-rays" to see the interior of earth?
Definition
seismic waves
Term
What happens to seismic waves as they travel through the interior?
Definition
they are reflected, refracted and diffracted as they go through Earth's interior.
Term
How can the speed of waves give info?
Definition
they can help determine the kind of rock inside earth & how hot it is
Term
Moho
Definition
boundary between the crust and the mantle
Term
what is the difference between longitudinal waves and transverse waves?
Definition
[image]
Term
more amplitude equals _______
Definition
more energy
Term
waves that require a medium are _____. Three types of those waves are ______, _______ and _______.
Definition
waves that require a medium are Mechanical Waves. Three types of those waves are sound, seismic and ocean.
Term
waves that can go through empty space are ______. 2 examples of those are ______ and _______.
Definition
waves that can go through empty space are electromagnetic waves. 2 examples of those are ultraviolet (UV) rays and infared (IR) waves
Term
What is the EM spectrum from low frequency ---> high frequency
Definition
radio -> micro -> IR -> visible -> UV -> x-rays -> gamma
Term
describe the Modified Mercali Scale.
Definition
Intensity Scale. qualitive observations. least precise. based on peoples reactions.
Term
describe the Richter scale
Definition
quanititave observation. based on wave amplitude and log scale. (amplitude x10 and energy x32)
Term
Moment Magnitude Scale
Definition
quanititive observations. most precise. based on more than 1 meausurement.
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