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Earthquake Hazards:

Objectives:

    1.    Summarize earthquake hazards and the damage they can cause.

    2.    Explain how safe building practices and earthquake prediction can prevent earthquake damage.

Key terms:

    liquefaction    aftershock    tsunami    seismic gap

Notes: (10-30

Earthquake Hazards

For people living in earthquake hazard zones, earthquakes can be both frightening and potentially life threatening.    Although in the United States we have made tremendous strides in the fields of earthquake preparedness and building safety, the potential for damage and loss of life still exists.  Earthquake risk maps are used by geologist and building planners to better design communities while reducing the risk to its members.

Southern California Earthquake Risk Map

(www.californiahistory.org/ earthquake-risk.jpg)

Liquefaction

During the ground shaking some of the dirt takes on the properties of a liquid. 

Buildings loose their foundation
Can trigger massive landslides

(www.lettis.com/images/ similiq.gif)

Tsunamis

Large underwater or costal earth quakes can create immense tidal surges (tidal waves).  The resulting wave travels very quickly across the ocean.  

1946 earthquake in the Aleutian Islands created a  tsunami that killed 159 people in HI
The wave traveled ~ 750km/hr

(www.tsunami.org/images/maps/ 46_runups_oahu.gif)

Preventing damage

Damage to structures and individuals have been greatly reduced by the adoption and implementation of building codes designed to relieve the stress of buildings and foundations following an earthquake.

Predicting Earthquakes:

The prediction of earthquakes relies on three factors.

where
when
prediction of magnitude

Assumptions used in the prediction of earthquakes.

earthquakes are periodic events - helps cities assess risks and adjust building codes 
seismic gaps - areas in a fault that do not release pressure (earthquakes) are more likely to have large earthquakes in the future.

 

 

 

 

 
 

 

Last modified: February 26, 2003