Why are earthquakes so destructive?

Ground motion is both horizontal and vertical. Horizontal accelerations are often greater than vertical accelerations.

Video 1 Click on the video above of a shake table test run at UC San Diego (courtesy of Professor Andre Filiatrault, University at Buffalo).

Video 2 Click on the video above of a shake table test run at UC San Diego (courtesy of Professor Andre Filiatrault, University at Buffalo).

Damage depends in large part on: -- the size of the earthquake -- distance from the focus -- local construction techniques

Wave propagation West Coast of USA: Earthquakes are more frequent Seismic waves propagate shorter distances

Wave propagation East Coast of USA: Earthquakes are less frequent Seismic waves propagate longer distances

Patrick Abbott, Natural Disasters, 4e, page 147

World-wide distribution of population USA Concentration of earthquakes along the west coast Concentration of population along the west coast, the east coast, great lakes region, southwest

World-wide distribution of population Concentration of earthquakes along the ‘ring of fire’ - the Pacific rim Concentration of population along the Pacific rim - - Japan, Korea, Taiwan, Hong Kong/China, Philippines, Indonesia

World-wide distribution of population Concentration of earthquakes in the Mediterranean region Concentration of population in Spain, Italy, Greece, Turkey, Armenia, Iran

Construction techniques Building codes vary greatly, from very stringent to nonexistent. (Poor) countries often don’t follow the building codes that they do have.

Bhuj, India, 2001 -- Patrick Abbott, Natural Disasters, 4e, page 2

Berkeley, CA - 1989 -- Patrick Abbott, Natural Disasters, 4e, Note the reinforcing rods which are not tied together.

Earthquakes don’t kill, buildings do.

Mexico City, 1985 -- Patrick Abbott, Natural Disasters, 4e, page 100 This WAS a seven story building - count the floors.

Patrick Abbott, Natural Disasters, 4e, page 85 Would you want to work in this building in California?

The following material is from How Does Earth Work The following material is from How Does Earth Work?, Gary Smith and Aurora Pun, Prentice Hall, 2006, pp. 299-ff

Why are earthquakes so destructive? Many people live in earthquake country. People build and occupy unsafe houses and buildings. Communities are not prepared for the aftermath of earthquakes, especially fires.

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