One of my recent assignments was to write a report in essay format about tsunamis and tsunami detection.

Adrian 7A

Due March 1st

Early Warning: Tsunamis

            In 2004, a giant wave hit 14 countries including Indonesia, Sri Lanka India, Thailand and many more. In Sri Lanka alone, it destroyed 100,000 homes and demolished two thirds of the fishing fleet. What was this “giant wave,” and what caused it? Is there anything that can be done to prevent them? In this report I will cover three different branches of the topic of “giant waves”: what they are, how they are detected, and some notable or historical ones.

            The giant wave that I described in the first paragraph was a tsunami. The word tsunami is defined by Princeton.edu as “a destructive sea wave caused by an earthquake or volcanic eruption”. In other words, a tsunami is a large, powerful wave that was created by an undersea earthquake or volcanic eruption. They can also be caused by landslides and even explosions from undersea bomb tests. More specifically, the waves are created when lots of water is displaced because of the earthquake, volcanic eruption etc. For example, during an earthquake a tectonic plate can “flip up” because of pressure from another tectonic plate. However, when it “flips up”, it displaces, or moves a lot of water out of the way. The water is moved at great force, which forms the tsunami. One interesting fact is that tsunamis start out with a very long wavelength and short amplitude, which means that they are hard to detect visually out at sea and are long and flat. However, as they move closer to shore their wavelength decreases and the amplitude increases, which makes the waves taller and easily detectable.

Because tsunamis are caused by nature instead of humans (except for explosions), they are not preventable. However, they are somewhat detectable, so humans can get an early warning and escape the tsunami. One method that is used to detect tsunamis is through the use of seismic gauges which detect the earthquakes that can cause tsunamis. However, not all earthquakes lead to a tsunami, which means that a seismic gauge’s readings wouldn’t always be useful. To predict a tsunami, there are two general types of detectors that are the most used. “Pressure recorders,” which detect the weight of all the water above it, and “tide gauges”, which are measure the height of the sea level from the sea floor as well as other conditions. The pressure recorders look for a dramatic increase in total weight of the water above it. If a large increase is detected, it probably means that there is a tsunami above it. The tide gauges have an extremely long cable attached to the seafloor, all the way up to the buoy. The cable is used to detect the distance of the sea level from the sea floor. When there is a large increase, it means there is probably a tsunami. In that way, the two devices are similar. Both of these devices are used to detect a tsunami from far out, where the tsunami is difficult to detect. As a tsunami approaches the coast, it “sucks in” the water from the coast (in other words, the water will retreat), so a tsunami is easily detectible then, although it is at the last minute. As a final word, there is no guaranteed-to-work method of detecting tsunamis, and so tsunamis will continue to be a problem in the foreseeable future.

The most famous tsunami in history is surely the 2004 tsunami in Southern Asia which was mentioned in the first paragraph. It killed more than 150,000 people, but more than $7 billion dollars were pledged to be donated. Interestingly, a BBC article from 2005, a year later, stated that there was a shortfall of over $4 billion of the money that was pledged to be donated. The earthquake that caused the tsunami was 9.1 on the Richter scale, which makes it the third largest earthquake ever recorded, behind earthquakes in Chile and Alaska. Another notable tsunami was the 1999 Tsunami in Turkey, which was caused by a 7.6 level earthquake, and killed 17,000 people.

An additional notable tsunami was the 2006 tsunami in island of Java. This tsunami only claimed 500 lives, which is small compared to other tsunamis, but it was significant because it took place a year and a half after the tsunami in Southern Asia, yet it was not detected early enough to give the residents of Java time to evacuate. This showed the failure of the network of tsunami detectors that was built after the 2004 tsunami. Since then, more pressure sensors, seismological stations and other tsunami detecting hardware have been built.

To conclude, tsunamis are interesting but unfortunate natural disasters. They are often difficult to detect, and they have the power to kill thousands of people, as evidenced by the 2004 earthquake in Asia. They are out of our power like any other natural disaster, but with developing technology, our ability to detect them has gotten much better. Although it won’t come soon, maybe someday we’ll live in a world where tsunamis are detected days ahead of their arrival, and they won’t kill people anymore because all people would have been evacuated.

Sources:

2005, February. "2004 Indian Ocean Earthquake and Tsunami." Wikipedia, the Free Encyclopedia. Web. 28 Feb. 2011. .

BBC. "BBC NEWS | Asia-Pacific | Tsunami Aid Shortfall over $4bn." BBC News - Home. 18 Mar. 2005. Web. 28 Feb. 2011. .

Princeton. "Definition of Tsunami." World Net Web from Princeton. Web. 28 Feb. 2011. .

Columbia Encyclopedia. "Tsunami - Credo Reference Topic." Credo Reference Home. Web. 28 Feb. 2011. .

"Famous Tsunamis · Mega Tsunamis." Astrology Weekly - Astrology Articles and Information Updated Weekly. Web. 28 Feb. 2011. .

"BBC NEWS | Science/Nature | Indian Ocean Tsunami Warning System." BBC News - Home. 23 Dec. 2005. Web. 28 Feb. 2011. .

Smith-Spark, Laura. "BBC NEWS | Asia-Pacific | Indonesia Tsunami System 'not Ready'" BBC News - Home. 19 July 2006. Web. 28 Feb. 2011. .

"BBC NEWS | Asia-Pacific | Tsunami Aid: Who's Giving What." BBC News - Home. 27 Jan. 2005. Web. 28 Feb. 2011. .

Side note: I think my fingers are tired of typing T's before S's now. It feels so unnatural.