VIEW: Earthquake Damage

Earthquake Damage

The type of construction has a tremendous effect on what happens during an earthquake. Damage and deaths are directly affected by construction in an earthquake. 

Enormous damage was done in the 2011 Christchurch, New Zealand earthquake, whereas when the same magnitude earthquake struck Iceland, far less was damaged. Photos courtesy of CK-12. 

We know that earthquakes kill a lot of people. However, the ground shaking almost never directly kills people. Fatalities depend on the earthquake's size, the type of ground people inhabit, and the quality of structures that are built in the area.  Most damage is done and more people are killed by fires or tsunamis that can follow an earthquake, and by structures falling on them. 

There are several characteristics that make an earthquake deadly. The first is population density.  The more people that live in an area, the greater the potential for a lot of deaths. The magnitude 9.2 earthquake in Alaska in 1964 resulted in only 131 deaths because there were few people that lived in the area. Size (but not all large quakes result in large numbers of fatalities). The Indian Ocean earthquake in 2004 was one of the largest ever, but most of the fatalities were caused by the subsequent tsunami.  Ground type is also a factor. Solid bedrock vibrates less than soft sediments, so there is less damage on bedrock. Sediments are subject to liquefaction and bedrock is not. 

In earthquake-prone areas, city planners try to reduce hazards. For example, in the San Francisco Bay area, maps show how much shaking is expected for different ground types. This allows planners to locate new hospitals and schools more safely. 

Map showing intensity of ground shaking expected during an earthquake in the San Francisco Bay area. Map courtesy of CK-12. 

Watch the following video.

Source: Earthquake Damage. Retrieved from http://www.ck12.org/earth-science/Earthquake-Damage/lesson/Earthquake-Damage/r22/ on January 25, 2014.