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

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

What is an earthquake? Used to describe both sudden slip on a fault, and the resulting ground shaking and radiated seismic energy caused by the slip Caused by volcanic or magmatic activity, Caused by other sudden stress changes in the earth.

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.

Map of Tectonic Plates and Volcanoes

Three Types of Faults Strike-Slip Reverse Normal

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

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

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 Seismometers work 1. Detects and records the ground motion 2. A large mass is suspended from a wire. It does not move during an earthquake. (all because of inertia) 3. A pen attached to the mass marks a roll of moving paper.

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

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

Comparing Seismic Waves

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- Triangulating the Epicenter 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

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