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Earthquakes! **Adapted from

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1 Earthquakes! **Adapted from

2 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 magma activity, Caused by other sudden stress changes in the earth.

3 Three Types of Faults Strike-Slip Thrust Normal

4 What causes earthquakes? Tectonic plates move past each other causing stress. Stress causes the rock to deform, break, and/or move

5 Elastic Rebound – deformed rock goes back to its original shape

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

7 How Seismographs Work the pendulum remains fixed as the ground moves beneath it

8 Typical Seismogram

9 Primary Waves (P Waves) PUSH-PULL PATTERN! – A type of seismic wave that pushes & pulls the ground The FIRST wave to arrive from an earthquake—travels the fastest! Travels Parallel to the direction the wave travels

10 Secondary Waves (S Waves) A type of seismic wave that moves the ground up and down or side-to-side (perpendicular) to the direction the wave travels Slower! More destructive to buildings


12 Comparing Seismic Waves **P & S Wave song:

13 Surface Waves Move along the Earth’s surface – ROLL OUT! Motion can be up and down, around & back & forth Travel more slowly than S and P waves – Last to arrive Most destructive to structures

14 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

15 Locating Earthquakes

16 Locating Earthquakes

17 Locating Earthquakes

18 How are Earthquakes Measured? Richter Scale-measures energy

19 How are Earthquakes Measured? Mercalli Scale-measures damage Click Link for Interactive Demo

20 Earthquake Waves & Earth’s Interior **See how seismic waves move through the Earth’s layers here (Shadow zone):

21 Seismic Waves in the Earth

22 Tsunamis

23 Formation of a tsunami

24 Tsunami Warning System

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