Atmosphere And Weather
Earthquake damage in Seward, Alaska

The Reason Earthquakes are so Destructive



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Earthquake damage in Seward, Alaska
Rex Trulove's image for:
"The Reason Earthquakes are so Destructive"
Caption: Earthquake damage in Seward, Alaska
Location: 
Image by: United States [Air Force]
© public domain http://commons.wikimedia.org/wiki/File:Seward_earthquake_damage.jpg

Both hurricanes and earthquakes can be devastating in property damage and in lives lost. However, earthquakes often cause more destruction than hurricanes, and it can make a person to wonder why this is. It is easiest to first look at each of these to arrive at a reason.

Hurricanes

Hurricanes can span hundreds of miles. With rotating and extreme winds, plus a curving path, they can cause damage over a large area. Heavy rains and tornadoes often accompany a hurricane, increasing the danger. Also, hurricanes form over the ocean, so they usually push a wave of water ahead of the base of the storm, creating a storm surge that can cause more destruction than the storm itself.

Between the storm surge, the tornadoes and the high winds, homes and properties can be battered. Flood damage is common, and buildings can have windows blown out. It isn't uncommon to have roofs blown off or to end up in such bad shape that they may need to be replaced, assuming that the structural integrity of the building also hasn't been destroyed.

Low laying areas are especially at risk due to both the wind and the water. Even trees can be washed away, becoming that much more dangerous in the storm surge.

The single bright spot is that usually, once the hurricane has moved away from its energy source, which is the warm water, it begins to lose strength. The storm can stall and last for days, but it will eventually either dissolve or move back out to sea.

Earthquakes

An earthquake also impacts a large area, though for different reasons. A major quake is triggered when tectonic plates, held tightly together and partly fused, suddenly release, allowing a great deal of energy to travel in waves in all directions. The plate fracture zone, or fault fracture, can be hundreds of miles long.

The seismic waves are in three forms in the quake. The two that often cause the greatest damage are an up and down motion and a side to side motion. It isn't uncommon for a building or structure to withstand one of these, but to collapse from the other. With a big quake, it isn't just damage to the buildings, but total destruction of them.

The waves also spread out, like ripples in a pond when a rock is tossed in, so they can cause damage many miles from the site of the original earthquake.

In addition, earthquakes cause ruptures in water and sewer lines, and in gas lines, either directly or through liquefaction. Liquefaction is when the ground is shaken and becomes almost fluid, not able to support pipes or buildings. Building often collapse because of this when the foundation is not solid anymore or has been undermined. The broken lines can lead to huge fires, without a water supply to fight them.

What is more, it is rare for an earthquake to have a single jolt. Usually there are aftershocks for weeks or months. Some of the aftershocks can be stronger than the original quake. If buildings and roads have already been weakened by the original waves, the aftershocks can cause even more severe damage.

Comparison

Neither hurricanes nor quakes are things most people would want to go through. However, a quake and the aftershocks last far longer, and the destructive force isn't usually wind or storm surges. Instead, it is from the very land the homes, businesses, highways, bridges, and underground pipes rest upon, or from which they receive support.

Hurricane Katrina caused enormous damage. There were many deaths, and the destruction is still in evidence. The San Francisco quake of 1903 leveled huge parts of the city to the ground and caused the incineration of even more of the city. Many of the crushed bodies were never recovered. Jolts were felt long after the main quake, and hindered both rebuilding and rescue efforts. There is still evidence of this disaster, over a century later.

There are reasons that earthquakes cause more damage than hurricanes, though it is doubtful people would want to experience either. They are both destructive.

Additional sources:

United States Geological Survey
Lewis Ansell, geologist, dec.
National Geographic

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ARTICLE SOURCES AND CITATIONS
  • InfoBoxCallToAction ActionArrowhttp://www.nhc.noaa.gov/surge/
  • InfoBoxCallToAction ActionArrowhttp://vulcan.wr.usgs.gov/Glossary/Seismicity/what_causes_earthquakes.html
  • InfoBoxCallToAction ActionArrowhttp://www.geo.mtu.edu/UPSeis/waves.html