# Glencoe Chapter 9 ©2005 LikeScience.com. Faults Rocks break and move along surfaces called faults.

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Faults Rocks break and move along surfaces called faults.

Earthquakes Vibrations caused by breaking of rocks along faults.

Types of Faults Normal Faults: –Force: Tension –Direction: Apart Reverse Faults –Force: Compression –Direction: Together Strike-slip Fault: –Force: Shearing –Direction: Sliding

Normal Faults

Reverse Fault

Strike-Slip Fault

Seismic Waves Vibrations caused by earthquakes.

Earthquake Focus The point in the Earth’s interior where the is energy release occurs.

Primary Waves: Waves that move through Earth by causing particles in rocks to move back and forth in the same direction the wave is traveling.

Secondary Waves Move through Earth by causing particles in rocks to move at right angles to the direction of the wave.

Surface Waves Move by giving particles an elliptical motion, as well as a back-and-forth swaying motion.

Epicenter The point on Earth’s surface directly above an earthquake’s focus.

Locating an Epicenter 1. S-P Interval: Take the difference in arrival time of the primary and secondary waves. 2. Find the distance from the seismic station and the epicenter. For 3 stations. 3. Plot the distances as radii on three circles. Where they meet is where the epicenter is located.

S-P Interval

Find Distance

Plot Epicenter

Seismologist Scientist who studies earthquakes.

Seismograph Instrument used to measure the vibrations caused by earthquakes

A mile or so below you there are large pieces of the Earth’s crust known as __________________. Plates

They move and float on a river of ______________ in the Earth’s _______________. Magma Mantle

Where these plates break a ______________ will form. Faults

At ______________ plate boundaries ___________ forces cause reverse faults to form. Convergent Compression

At transform plate boundaries __________ forces cause __________ faults to form. Shearing Strike-Slip

Lastly, as tension forces act on the plates at ___________________ plate boundaries, __________ faults form. Divergent Normal

As plates interact they sometimes produce large vibrations known as __________. Earthquakes

The _________ is the location under the ground where the energy of the vibrations was released. Focus

The point on the surface directly above this location is known as the ____________. Epicenter

_____________, scientist who study earthquakes use instruments called _______________ to measure the vibrations caused by earthquakes. Seismologist Seismograph

The first wave of energy released by an earthquake is a _______________ wave. Primary

P-waves travel in a _________ motion. Side to Side

Second to arrive at the _________ station is the ____________ wave Seismic Secondary

These waves travel in a __________ motion. Up and Down

The seismic wave that causes the most damage is the ________________ wave. Surface

Scientist read _____________ to determine the difference in the arrival time of the ___________ wave and the _____________ wave. Seismograms P-wave S-wave

Once they have determined the __________________ they use a chart to determine the distance the ____________ station was located from the _______________. S-P interval Seismic Epicenter

The height of the _________ on the paper tells the ___________ of the earthquake. __________ use the _________ scale to measure the magnitude of earthquakes. Lines Magnitude Richter

Because the _______________ waves caused by earthquakes move out in all directions, scientist must have measurements from __________ different __________ stations. Seismic 3 seismic

Once they have the measurements they use a _____________ and plot the distance as a radius out from each seismic station. Map

Where these circles cross the _________________ of the earthquake is located. Epicenter

If a(n) ____________ takes place under ________________ a _______________ can take place. Earthquake Water Tsunami

This large wave can reach _________ meters in height. 30

The ___________ plates that make up the earth’s ___________ are on top of the Earth’s ___________. Tectonic Crust Mantle

Below the Mantle is the _________ core and _________ core. Outer Core Inner Core

The ______ core is composed of _________ and _________ and is liquid. Outer Core Iron Nickel

The _______ core is also composed of __________ and ________ but is solid. Inner Iron Nickel

The mantle is made mostly of _______, __________, _____________ and _________. Magnesium Silicon Oxygen Iron

______________ ___________ is the boundary between the crust and mantle Moho Discontinuity

___________ waves speed up because they are passing into the __________ which is the rigid __________ and upper ______________. Seismic Lithosphere Crust Mantle