EARTHQUAKES&

VOLCANOES

What is it?

Earthquake – is the shaking a trembling that results from the sudden movement of part of the

Earth’s crust.

http://www.youtube.com/watch?v=cavq2HFBa-U&feature=fvsr

Did you know?

One million earthquakes happen in a year

one thousand every year makes the earth move

twenty can cause severe damage.

Faulting & Earthquakes

Faulting causes earthquakes.

San Andreas Fault – land to the west is moving north and the land to the east is moving south

Tsunami’s & Earthquakes

Tsunamis – earthquakes that occur on the ocean floor produce giant sea waves called tsunamis.

Parts of an Earthquake

Focus – the point beneath the Earth’s surface where the rocks break and move.

Epicenter – directly above the focus, on the Earth’s surface

Seismic Waves

Also known as Earthquake Waves

#1 Primary Waves

Fastest wavesP wavesMoves through solids, liquids, and gases

Speeds up in denser material

Push and pull waves

#2 Secondary Waves

S wavesSlower than P wavesTravels through solids but not liquids and gases

Speeds up in denser material

Movement is side to side

Modeling P and S Waves

S waves: do "the wave" as they would in a football stadium, raising their arms and lowering them as the next person raises his or hers.

P Waves: gently grip each other's shoulders and having one pull or push the next person in line.

#3 Surface Waves

L wavesSlowest wavesOriginates at the epicenterCreates the wave movements in the Earth’s surface

Causes the most damage

Measuring Seismic Waves

Seismograph – is an instrument that detects and measures seismic waves

Seismologist – scientists who study earthquakes, can determine the strength of them