Date post: | 17-May-2015 |
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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