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Tsunami and Earthquake Hazard 10/27/148-3 pgs. 205-210 and pg. 376
• IN: Can seismologists predict earthquakes? Why or why not?
• Tsunami – a wave that forms when a large volume of ocean water is suddenly moved up or down.
• This movement can be caused by underwater earthquakes, volcanic eruptions, landslides, underwater explosions, or the impact of a meteorite or comet.
• As it enters shallow waters tsunami wave speed slows and its height increases, creating huge destructive waves.
• Tsunami Animation
• Earthquake hazard measures how prone an area is to experiencing earthquakes in the future.
Earthquake Hazard• An area’s earthquake-hazard level is
determined by past and present seismic activity.
Nationwide Earthquake Frequency
Worldwide Earthquake Frequency
Recent Earthquakes
• Earthquakes
Worldwide Earthquake Frequency(Based on Observations Since 1900)
Descriptor Magnitude Average occurring annually
Great 8.0 and higher 1
Major 7.0-7.9 18
Strong 6.0-6.9 120
Moderate 5.0-5.9 800
Light 4.0-4.9 about 6,200
Minor 3.0-3.9 about 49,000
Very minor 2.0-2.9 about 365,000
• Richter magnitude scale - Wikipedia, the free encyclopedia
Earthquake Forecasting
• Gap hypothesis – states that sections of active faults that have had relatively few earthquakes are likely to be the sites of strong earthquakes in the future.
• Seismic gaps – an area along a fault where relatively few earthquakes have occurred.
Earthquakes in Nevada
Earthquakes and buildings
• Buildings are designed to withstand earthquakes by flexibility and ability to absorb shock.
Being prepared
• Always keep emergency kit.• Keep heavy objects low/fastened.• Duck and cover
• OUT: How does the frequency of an earthquake compare to the magnitude of the earthquake?