Geology And Geophysics

Recent Earthquakes may Herald more to come



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Recent earthquakes in Chile, Taiwan, Haiti, and now Turkey and other areas raise the concerns of many across the globe. What is happening to our world? Does this herald the end of this planet and life as we know it? While scientists dismiss these events as a normal part of the process, others are beginning to wonder just want is going on. That our planet is undergoing drastic change is no longer in doubt. Where we are headed is anybody’s guess, but one thing is sure-we may be on the cusp of major earthquake activity, and as a consequence increased volcanic activity might answer the issues produced by global warming.

The notorious “Ring of Fire” is the area around the Pacific Basin which produces some of the largest earthquakes (about 80%) and tsunamis on the planet. Earthquakes are produced when the earth’s tectonic plates shift against or collide with each other. Scientists have mapped these fault lines all over the world, and many might be surprised where they are located. An interesting but little known fact is that this stress builds and is usually unnoticeable, until it suddenly erupts into tremendous destruction. Major cities, nuclear reactors, and some of the heaviest population centers on the planet lie atop some of the largest faults.

Seismologists measure earthquakes on a scale of magnitude which indicates severity of the quake. A magnitude 3-4 is considered minor, 5-7 moderately strong, a quake of 7-8 is major and 8 or above is great. Earthquakes are a year (220,000 in 2004, 73,000 in the Kashmir quake in October) from the destruction including collapsed buildings, mudslides, fires, floods, and tsunamis.

The Chilean quake was 500 times more powerful than its counterpart in Haiti, but produced significantly less damage due to better structural planning and preparations. Chile’s tremor was the 5th largest on record. Scientists estimate that the Chilean quake shifted the earth’s axis by three inches and shortened the day 1.26 millionth of a second. By comparison the earthquake in Sumatra in 2004 was rated a 9 and shortened the day by 6.8 millionths of a second.

The destruction in Haiti was worse due to many factors. The quake was relatively shallow, about 5 miles beneath the surface, which increased the shaking on top of the island. The lack of building codes with minimal structural design to withstand large earthquakes resulting in much of the infrastructure, including the Presidential Palace, crumbling into ruins. Haiti’s plight was unusually great and a bit surprising since it is not located on the Pacific Basin, long the location of some of the largest quakes in the world.

While notoriously difficult to predict, the clustering of major quakes of 6.7 or greater in the southern California area lead experts to predict that a major quake is about 67% likely in the next 30 years. Clusters of 4 or more earthquakes of 6-6.5 magnitude preceded the great San Francisco earthquake in 1911 in the 75 years leading up to the make occurrence. The possibility of destruction and even death will depend largely on where the epicenter is located and the severity of the quake.

Sources:

http://www.usgs.gov/newsroom/article.asp?ID=2378

http://news.nationalgeographic.com/news/2010/03/100302-chile-earthquake-earth-axis-shortened-day/

http://pubs.usgs.gov/gip/earthq1/predict.html

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  • InfoBoxCallToAction ActionArrowhttp://video.nationalgeographic.com/video/player/environment/environment-natural-disasters/earthquakes/earthquake-101.html
  • InfoBoxCallToAction ActionArrowhttp://environment.nationalgeographic.com/environment/natural-disasters/earthquake-profile.html
  • InfoBoxCallToAction ActionArrowhttp://ngm.nationalgeographic.com/2006/04/earthquake/achenbach-text/3
  • InfoBoxCallToAction ActionArrowhttp://pubs.usgs.gov/gip/earthq1/predict.html
  • InfoBoxCallToAction ActionArrowhttp://www.usgs.gov/newsroom/article.asp?ID=2378
  • InfoBoxCallToAction ActionArrowhttp://news.nationalgeographic.com/news/2010/03/100302-chile-earthquake-earth-axis-shortened-day/
  • InfoBoxCallToAction ActionArrowhttp://pubs.usgs.gov/gip/earthq1/predict.html