Earthquakes

Berks County Earthquakes

• Sinking Spring – 12 /13/06 Felt at Wilson Southern 2.8

• Spring Township 10/29/96 2.5

• Spring Town. 2/1/96 2.3 and 4 more

• Whitfield 1/15/94 4.6

• Sinking Spring 1/7/54 4.0

Millersville Seismograph

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Earthquakes in Pennsylvania

• Web Sites

• Maps of PA

• Maps of Eastern U.S.

• Earthquake Map of U.S.

• Real-Time Seismograph from Millersville

Earthquake Photos

• Web Photos

Italy 2002

Earthquakes

• Rocks bend, compress, and stretch from movement caused by forces in the Earth.

• Earthquakes can not be accurately predicted.

Earthquakes: Locations

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Earthquake Vocabulary

• Shadow zone: a region that does not receive any earthquake waves

• Richter Scale – evaluates earthquake energy.

• Mercalli Scale – evaluates earthquake damage.

• Seismologist – scientist who studies earthquakes

Waves

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Earthquake Vocabulary

• P-Wave = primary,arrive first, move in the direction of the wave .

• Secondary Waves = particles in rocks move at right angles to the direction of movement.

• Epicenter = The point on the Earth’s surface which is directly above the focus.

• Focus = The point in the Earth’s interior where energy is released.

Wave Forms

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Earthquake Vocabulary

• Faults – once the elastic

limit of rocks is passed,

• they break and move along

surfaces called faults.

Earthquakes• Magnitude- each level is 32 times more powerful;

8 is 32 x more powerful than a 7.• A Seismograph measures Magnitude.

• Compression – a force that squeezes and compresses.

Vocabulary

• Tension – is the stress that causes stretching and elongation.

• Shear – is the force that causes slippage and sliding.

Faults

• Normal Faults – are caused

by tensional forces.

• Reverse Faults – are caused

by compression forces.

P-Waves of Earthquakes

• Primary Waves – the first waves that reach a seismograph.

Vocabulary

• Three seismographs are needed to locate an earthquake epicenter.