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10 Reasons Why Bridges Collapse


10
Earthquake

Earthquakes cause damage to all structures, including bridges. Major earthquakes can bring about the collapse of dozens of buildings, but collapsed bridges are often the most visible signs of the havoc an earthquake can wreak. Amidst the rubble and devastation, the sight of a damaged bridge from TV news helicopters stands out and becomes the iconic image of that particular disaster.

Such is the case with the Loma Prieta earthquake that struck the California coastal cities of Oakland and San Francisco in October 1989. The earthquake -- named for a nearby mountain -- caused 63 deaths, and the majority of them occurred in two bridge collapses: One person died as a section of the San Francisco-Oakland Bay Bridge gave way, and 42 others perished when a large portion of the Cypress Street Viaduct carrying Interstate 880 collapsed [source: USGS].

Fortunately, earthquake-triggered bridge collapses are relatively rare. In addition, builders can construct bridges in earthquake-prone areas to withstand tremors -- or at least minimize the loss of life when one occurs.


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