Earthquakes
Berks County Earthquakes
• Sinking Spring – 12 /13/06 Felt at Wilson
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Southern
2.8
Spring Township 10/29/96
Spring Town.
2/1/96
Whitfield
1/15/94
Sinking Spring 1/7/54
2.5
2.3 and 4 more
4.6
4.0
Millersville Seismograph
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Earthquakes in Pennsylvania
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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.