June 12, 2005

Cascadia: Living on Fire [Synopsis]

I am sure that by now you are all wondering, "Why so many school reports," and such. I figure that maybe, someday it might help someone with on of their reports, somewhere in the English speaking world.


The article, Cascadia: Living on Fire, by Rick Gore, dealt with geological evidence that could be pointing to ward a major earthquake in an area known as Cascadia as well as several other natural disasters that the earthquakes can cause, including tsunamis, and volcanic eruptions.
Cascadia ranges from northern California, where the Cascade Mountains first begin, to British Columbia, where the Cascades end. The creation of the Cascade Range is related to the subduction of the Juan de Fuca plate beneath the North American plate. This causes volcanoes to erupt, mountainous peaks to form, and earthquakes to rattle the ground, damaging buildings and property.
As one plate slides under another they may become locked, or unable to continue sliding. Since locked plates continue to push against one another pressure begins to build along the fault. Rocks are pushed upwards several feet of where they once were, over a period of hundreds of years. When the rocks cannot continue to store the pressure, or stress, they break and rebound to their original positions causing an earthquake. The magnitude, or size, of the earthquake is dependant upon how much stress has been released during the earthquake. Earthquakes of larger magnitudes cause greater amounts of shaking than earthquakes of lower magnitudes, and vise versa. These earthquakes have been known to occur independently of any other region along the fault, but now some scientists are beginning to believe that in the past major earthquakes have occurred in which the entire fault released pressure all at once.
Earthquakes can cause another serious natural disaster, tsunamis. When the land rebounds, sometimes back into the ocean, it replaces areas where hundreds of cubits of water stand, forcing the water to move. The sudden move results in any large waves that cover the shoreline. In a large earthquake, such as one that is believed to occur during a large fault earthquake, tsunamis could nearly wipe out entire costal towns, causing destruction and killing hundreds of people. It is for this reason that many of these towns are setting up tsunami evacuation routs, leading to elevated ground, in hopes to save lives during a large tsunami. Volcanic eruptions may also be caused by earthquakes as magma and gasses are loosed from the crater.
Evidence has been found, that points to the large tsunami triggering earthquakes in many areas. Along the Washington coastline, a forest of dead trees still stands. Scientists have shown that they died around 1700 due to a large amount of salt water choking their roots. By digging beneath the surface of the area a layer of ocean sand can be found on top of the original layers of dirt. A large tsunami is thought to have carried large amounts of salt water inland killing these trees. This tsunami is related in many ways to a large one that occurred in Japan, being that they both occurred at nearly the exact same time and date. Along with areas where land has dropped several feet, scientists are beginning to collect information about many large earthquakes in Cascadia’s past, leading them to believe that another big one could be on the way.

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