Earthquakes! **Adapted from
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
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
Typical Seismogram
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
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
Comparing Seismic Waves **P & S Wave song:
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
Locating Earthquakes
Locating Earthquakes
How are Earthquakes Measured? Richter Scale-measures energy
How are Earthquakes Measured? Mercalli Scale-measures damage Click Link for Interactive Demo
Earthquake Waves & Earth’s Interior **See how seismic waves move through the Earth’s layers here (Shadow zone):
Seismic Waves in the Earth
Tsunamis
Formation of a tsunami
Tsunami Warning System