How do particles move in the ground when an earthquake occurs?
back and forth, up and down, or in an eliptical motion parallel to the direction the wave travels
What are seismic waves?
released energy that travels as vibrations on and in Earth
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What do scientists use to classify seismic waves?
wave motion, wave speed, and type of material waves travel thru
Where is the epicenter of an earthquake?
found on Earth's surface directly above the focus of the earthquake
In what direction(s) from the focus do seismic waves travel?
outward in every direction
What happens to seismic waves as they travel away from the focus?
they decrease in energy and intensity
Why does the most damage occur close to the fault?
it is where the greatest amount of energy is found
What do people feel when an earthquake occurs?
the ground shaking
What are the three types of seismic waves?
primary, secondary, surface
Which type of wave causes the most damage at Earth's surface?
surface waves
Which type of wave is the fastest and travels through solids and liquids?
primary waves
Which type of wave travels only through solids?
secondary waves
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What kind of earthquakes occur at convergent continental/oceanic boundaries?
very deep and devastating quakes--release lots of energy
What kind of earthquakes occur at divergent boundaries?
shallow
What kind of earthquakes occur at convergent continental/continental boundaries?
varying depths, and can result in forming large mountain ranges
Where do most earthquakes occur?
in oceans and along edges of continents
What is a strike/slip fault?
2 blocks slide horizontally past each other in opposite directions--at transform boundaries
What is a normal fault?
forces pull blocks apart--hanging wall drops--at divergent plate boundaries
What is a reverse fault?
forces push blocks together--hanging wall rises--at convergent plate boundaries
What is the different between the focus and the epicenter?
focus -- where rocks first move along the fault below surface
epicenter -- above Earth's surface, directly above the focus
What are the characteristics of p-waves?
1. particles vibrate in same direction as waves
2. fastest and first to be detected
3. travel thru solids, liquids
What are the characteristics of s-waves?
1. particles move perpendicular to the motion of the wave
2. slower than P waves, faster than surface waves
3. travel thru solids
What are the characteristics of surface waves?
1. particles move in a rolling motion
2. slowest waves
3. cause greatest damage at Earth's surface
What discovery did learning about P-waves lead to?
The composition of the inner/outer cores
What discovery did learning about S-waves lead to?
The outer core is liquid because S-waves can't travel thru it
What did scientists learn about the mantle from studying seismic waves?
They were able to map convection currents, because the speed of the waves slows down in hot areas (like Mid ocean Ridge), and gets faster in cooler areas (like subduction zones)
What does the Richter Scale measure?
ground motion at a given distance from an earthquake to determine magnitude
What does the Moment Magnitude Scale measure?
total amount of energy released by an earthquake
What does the Modified Mercalli Scale measure?
the amount of damage that results from shaking based on descriptions of effects
What does the amount of energy released by an earthquake depend on?
1. size of fault
2. motion that occurs
3. strength of rocks
What are four indicators that seismologists use to determine earthquake risk?
1. past earthquake activity
2. geology around a fault
3. population density
4. types of buildings in an area
Explanation:
