Earthquakes Adapted from www middleschoolscience com What is

Earthquakes! **Adapted from www. middleschoolscience. com

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.

Three Types of Faults Strike-Slip Thrust Normal

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

Elastic Rebound – deformed rock goes back to its original shape http: //www. uwgb. edu/dutchs/Earth. SC-102 Visuals. Index. HTM

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

How Seismographs Work the pendulum remains fixed as the ground moves beneath it http: //www. uwgb. edu/dutchs/Earth. SC-102 Visuals. Index. HTM

Typical Seismogram http: //isu. indstate. edu/jspeer/Earth&Sky/Earth. Ch 11. ppt

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 http: //daphne. meccahosting. com/~a 0000 e 89/insideearth 2. htm

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 http: //daphne. meccahosting. com/~a 0000 e 89/insideearth 2. htm

Comparing Seismic Waves **P & S Wave song: http: //www. youtube. com/watch? v=w 3 NLex. Yx. R 7 g

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

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/Earth. SC-102 Visuals. Index. HTM

Locating Earthquakes http: //www. uwgb. edu/dutchs/Earth. SC-102 Visuals. Index. HTM

Locating Earthquakes http: //www. uwgb. edu/dutchs/Earth. SC-102 Visuals. Index. HTM

How are Earthquakes Measured? Richter Scale

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

Earthquake Waves & Earth’s Interior **See how seismic waves move through the Earth’s layers here (Shadow zone): http: //www. classzone. com/books/earth_science/terc/content/visualizations/es 1009 page 01. cfm

Seismic Waves in the Earth http: //www. uwgb. edu/dutchs/Earth. SC-102 Visuals. Index. HTM

Tsunamis http: //www. uwgb. edu/dutchs/Earth. SC-102 Visuals. Index. HTM

Formation of a tsunami http: //isu. indstate. edu/jspeer/Earth&Sky/Earth. Ch 11. ppt

Tsunami Warning System http: //isu. indstate. edu/jspeer/Earth&Sky/Earth. Ch 11. ppt