Ch 8& 9

What causes an earthquake
Earthquakes are caused by the vibrations of Earth produced by the sudden release of energy.
Describe the location of an epicenter and focus.
Epicenter is the location on the surface of Earth directly above the focus.
What is the elastic Rebound hypothesis? How dose it relate to earthquakes?
Elastic rebound hypothesis is the release of built- up energy. Most earthquakes are produced by the release of elastic energy stored in rocks that has been subjected to great forces.
Describe aftershocks and fore shocks
Aftershocks are small quakes that come after a major earthquake. Fore shocks are small quakes that come before a major earthquake.
How are earthquakes measured?
Historically, scientist have used two different types of measurement to describe the size of an earthquakes- intensity and magnitude.
Describe the following earthquake waves: surface, S waves, and P waves.
Surface waves= seismic waves that travel along Earth’s outer layers. They move up, down, and side to side. Most destrictive earthquake wave. Last to arrive at the seismograph.
S waves= Shake particles at right angles to their direction of travel. Also known as traverse waves.
P Waves = They push and pull rocks in the direction the wave travelers. Also known as compression waves. The order would be P,S,Surface
How do scientist locate earthquakes?
The difference in velocities of P waves provide a way to locate the epicenter. Scientist use a travel-time graph, in which one need at least 3 seismograph station data.
Where do most earthquakes occur?
Most of these earthquake occur around the outer edge of the Pacific Ocean. This zone is known as the circum-Pacific belt.
Describe each of the different scales used to measure earthquakes.
Intensity
What is liquefaction
Stable soil turns into a liquid that is not able to support buildings or other structure.
What causes tsunamis? What warning system is used
A tsunami is called a seismic sea wave.
What are some other dangers that can occur due to earthquakes
landslides and ground subsidence or the sinking of the ground triggered by the vibration occurs
Describe the layers of the earth
crust-lithosphere
the lithosphere consist of the crust and the uppermost mantle.
mantle- asthenosphere
soft,comparatively weak layer.
outer core- the core is liquid and is 2260 kilometers thick
inner core- solid layer having a radius of 1200 kilometers thick
Describe continental drift
hypothesis stated that the continents had once been joined to formed a single super continent.
who came up with the idea of continental drift
alfred wegner
what is pangaea
supercontinent
when did pangaea form
500 MY
what kind of evidence is present to verify the idea of continental drift
shortlines look like they fit together.
fossil organisms found on different landmasses.
several mountain belts end at one to reappear on a landmass across the ocean.
ancient climates.
What is pangeae
supercontinent
When did pangaea form
500 MY
who came up with the idea of continental drift
Alfred wegner