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?