24 The sensitive instruments used to record the vibrations of earthquakes are called SEISMOGRAPHS or SEISMOMETERS.
25 The record produced by a seismometer is called a SEISMOGRAM The record produced by a seismometer is called a SEISMOGRAM. This shows the arrival times of the different seismic waves at that location.
26 Primary waves or P-waves squeeze and pull rocks in the same direction along which the waves are traveling.
27 Secondary waves, or S-waves causes rocks to move up and down at right angles in relation to the direction of the waves.
28 P-waves are the fastest seismic waves P-waves are the fastest seismic waves. Remember P comes before S in the alphabet.
29 Some Important Earthquakes Lisbon, PortugalKilled 70,000 First Scientifically Studied EarthquakeNew Madrid, MissouriFelt over 2/3 of the U.S.Few Casualties
30 Some Important Earthquakes AlaskaKilled about 200Wrecked Anchorage.Tsunamis on West Coast.Tangshan, ChinaHit an Urban Area of Ten Million PeopleKilled 650,000
31 Major Hazards of Earthquakes Building CollapseLandslidesFireTsunamis (Not Tidal Waves!)