Earthquakes-8th Grade
Terms
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- After breaking, where do they move along?
- Faults
- What happens to rocks when they are applied force?
- They undergo stress.
- When the _______ ________ are passed, the rocks break.
- Elastic Limits
- On one side of a fault, which ways can rocks move.
- Up, down, or sideways
- Why do faults occur?
- Forces inside the Earth cause Earth's surface to move placing stress on or near the plate edge.
- At a fault, what will rocks do?
- Bend, compression, stretch, and possibly
- vibrations produced by breaking rock
- Earthquakes
- During an earthquakem what do the rocks do?
- Break, move along the fault, return to original position.
- Where do rocks move during an earthquake?
- Under, or along each other along fault lines
- What are the types of force that act on rocks?
- Tension, Compression, and shear
- Caused by rock above the fault moving downward in relation to the rock below the fault. Caused by tension forces
- Normal Faults
- Compression forces squeeze rock above the fault up and over the rock below the fault
- Reverse Fault
- Created by shear forces. rocks on either side of the fault move past each other without much upward or downward motion
- Strike-slip Fault
- Waves generated by an earthqauke can move the ground forward and backward, up and downm and side to side.
- Seismic Waves
- an earthquake's point of energy release
- Focus
- Cause particles inrocks to move back and forth in the same direction that the wave is traveling
- Primary Wave
- cause particles in rock to move at right angles to the direction of wave travel
- Secondary Wave
- move rock particles in a backward, rolling motion and a sideways swaying motion
- Surface Waves
- the point on the Earth's surface directly above the earthquake focus is called
- epicenter
- How do scientists the epicenter?
- they determine the different speeds of seismic waves
- Which waves move the fastest?
- Primary
- Which waves come after the first waves and before the last?
- Secondary Wave
- Which waves are the slowest?
-
Surface Waves
They also reach the station last. - What measures seismic waves?
- Seismograph
- What does a seismograph consist of?
- Rotating drum, and a pendulum with a pen
- The paper record of a seismic event is called a
- seismogram
- What is the Earth's outermost layer?
- Crust
- Why don't large areas of Earth receive seismic waves?
- the waves are bent or stopped by materials of different density
- Earthquake kill many people and cause much _________
- damage
- scientists who study earthquakes
- seismologists
- measure of energy released by an earthquake
- magnitude
- How is magnitude determined?
- Richter Scale
- The Richter Scale has no_________ ________
- Upper Limit
- Why are most Earthquakes not felt by humans?
- They have magnitudes to low.
- What is the Mercalli Scale?
- an intensity scale based on structural and geologic damage
- shaking from an earthquake can make wet soil act like a liquid
- Liquefaction
- What are tsunamis?
- Ocean waves are cause by earthquakes
- What cause tsunamis?
- a sudden movement of the ocean floor pushes against the water
- How far can tsunamis travel?
- thousands of kilometers in all directions
- Earthquakes cannot be__________
- predicted
- Buildings can be built to withstand ___________
- seismic vibrations
- What is a mooring?
- protect buildings from earthquakes. flexible. circular. made of alternating layers of rubber and steel