# Earthquakes Liz LaRosa 2009http://www.middleschoolscience.com for my 5 th grade science class 2009.

## Presentation on theme: "Earthquakes Liz LaRosa 2009http://www.middleschoolscience.com for my 5 th grade science class 2009."— Presentation transcript:

Earthquakes Liz LaRosa http://www.middleschoolscience.com 2009http://www.middleschoolscience.com for my 5 th grade science class 2009

What is an earthquake? The slipping and breaking of rock material along a fault. Faults are “cracks” in the crust near plate boundaries that are under stress. Stress is caused by the heat within the earth trying to escape and the movement of the plates.

Three Types of Faults Strike-Slip - shearing Thrust - Compression Normal – pulling away

What causes earthquakes? Tectonic plates move past each other causing stress. Stress causes the rock to deform – Plastic deformation – does not cause earthquakes – Elastic deformation – rock stretches then reaches a breaking point, releasing energy – kind of bounces back like a rubberband.

Elastic Rebound – deformed rock goes back to its original shape http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

Focus – point inside the Earth where an earthquake begins Epicenter – point on Earth’s surface above focus

Seismic Waves in the Earth http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

Primary Waves (P Waves) A type of seismic wave that compresses and expands the ground The first wave to arrive at an earthquake http://daphne.meccahosting.com/~a0000e89/insideearth2.htm

Secondary Waves (S Waves) A type of seismic wave that moves the ground up and down or side to side http://daphne.meccahosting.com/~a0000e89/insideearth2.htm

Typical Seismogram http://isu.indstate.edu/jspeer/Earth&Sky/EarthCh11.ppt

Comparing Seismic Waves

Surface Waves Move along the Earth’s surface Produces motion in the upper crust – Motion can be up and down – Motion can be around – Motion can be back and forth Travel more slowly than S and P waves More destructive

How do scientists calculate how far a location is from the epicenter of an earthquake? Scientists calculate the difference between arrival times of the P waves and S waves The further away an earthquake is, the greater the time between the arrival of the P waves and the S waves

Locating Earthquakes http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

Locating Earthquakes http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

Locating Earthquakes http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

Earthquake Waves & Earth’s Interior

How Seismographs Work http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM the pendulum remains fixed as the ground moves beneath it

How are Earthquakes Measured? Richter Scale

How are Earthquakes Measured? Mercalli Intensity Scale Click Link for Interactive Demo http://elearning.niu.edu/simulations/images/S_portfolio/Mercalli/Mercalli_Scale.swf http://elearning.niu.edu/simulations/images/S_portfolio/Mercalli/Mercalli_Scale.swf

Tsunamis http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

Formation of a tsunami http://isu.indstate.edu/jspeer/Earth&Sky/EarthCh11.ppt

Tsunami Warning System http://isu.indstate.edu/jspeer/Earth&Sky/EarthCh11.ppt