Проект "Цунами"

I.   Introduction

        Look at the view outside your window. The ground looks as if it is standing quite still, doesn’t it? But it isn’t. Our world is spinning round and round, like a huge top. And I paid attention to the fact, that, when I look at this beauty, my mood rises. The world around us is full of unexpected things. And the man can’t understand all of them. But instead of living in harmony with nature, he attempts to improve his laws and ways on Mother Earth.

1)  Definition of tsunami

The term tsunami comes from the Japanese, meaning "harbor" and "wave". The tsunami or tidal wave is a series of water waves (caused by the displacement of a large volume of a body of water, usually an ocean, but can occur in large lakes. Tsunamis are a frequent occurrence in Japan; approximately 195 events have been recorded.

3)  Reasons of Tsunami formation

        Tsunamis are caused by earthquakes, landslides, falling debris, volcanic explosions, bolides, glaciers, meteorites, nuclear tests.

        The main reason of tsunami formation is tectonic earthquakes. The deadliest natural disaster caused by the tsunami generated from an undersea earthquake on 26 December 2004 in the Indian Ocean has shaken up the world.

        Almost all the countries situated around the Bay of Bengal were affected by the tsunami waves in the morning hours.  

4)  Characteristics

        While everyday wind waves have a wavelength (from crest to crest) of about 100 meters and a height of roughly 2 meters, a tsunami in the deep ocean has a wavelength of about 200 kilometers. Such a wave travels at well over 800 kilometers per hour, but due to the enormous wavelength the wave oscillation at any given point takes 20 or 30 minutes to complete a cycle and has an amplitude of only about 1 meter. This makes tsunamis difficult to detect over deep water. Ships rarely notice their passage.

6. Warnings and predictions

        A Tsunami Warning System (TWS) is a system to detect tsunamis and issue warnings to prevent loss of life and property. It consists of two equally important components: a network of sensors to detect tsunamis and a communications infrastructure to issue timely alarms to permit evacuation of coastal areas.

        There are two distinct types of tsunami warning systems: international and regional. Both depend on the fact that, while tsunamis travel at between 500 and 1,000 km/h (around 0.14 and 0.28 km/s) in open water, earthquakes can be detected almost at once as seismic waves travel with a typical speed of 4 km/s (around 14,400 km/h). This gives time for a possible tsunami forecast to be made and warnings to be issued to threatened areas, if warranted

        In the 2004 Indian Ocean tsunami drawback was not reported on the African coast or any other eastern coasts it reached. This was because the wave moved downwards on the eastern side of the fault line and upwards on the western side. The western pulse hit coastal Africa and other western areas.

        A tsunami cannot be precisely predicted, even if the magnitude and location of an earthquake is known. Geologists, oceanographers, and seismologists analyze each earthquake and based on many factors may or may not issue a tsunami warning. However, there are some warning signs of an impending tsunami, and automated systems can provide warnings immediately after an earthquake in time to save lives. One of the most successful systems uses bottom pressure sensors that are attached to buoys. The sensors constantly monitor the pressure of the overlying water column.

7)  Stations

        Each DART station consists of a surface buoy and a seafloor bottom pressure recording (BPR) package that detects pressure changes caused by tsunamis. The surface buoy receives transmitted information from the BPR via an acoustic link and then transmits data to a satellite, which retransmits the data to ground stations for immediate dissemination to NOAA's Tsunami Warning Centers, NOAA's National Data Buoy Center, and NOAA's Pacific Marine Environmental Laboratory. The Iridium commercial satellite phone network is used for communication between 31 of the buoys. When on-board software identifies a possible tsunami, the station leaves standard mode and begins transmitting in event mode. In standard mode, the station reports water temperature and pressure (which are converted to sea-surface height) every 15 minutes. At the start of event mode, the buoy reports measurements every 15 seconds for several minutes, followed by 1-minute averages for 4 hours.

        The first-generation DART I stations had one-way communication ability, and relied solely on the software's ability to detect a tsunami to trigger event mode and rapid data transmission. In order to avoid false positives, the detection threshold was set relatively high, presenting the possibility that a tsunami with a low amplitude could fail to trigger the station.

The second-generation DART II is equipped for two-way communication, allowing tsunami forecasters to place the station in event mode in anticipation of a tsunami's arrival.

8)  Interesting facts

        I would like to represent the interesting facts concerning the behavior of animals and people. Not only animals are able to feel the sounds but people too.

        Some zoologists hypothesize that some animal species have an ability to sense subsonic Rayleigh waves from an earthquake or a tsunami. If correct, monitoring their behavior could provide advance warning of earthquakes, tsunami etc. However, the evidence is controversial and is not widely accepted. There are unsubstantiated claims about the Lisbon quake that some animals escaped to higher ground, while many other animals in the same areas drowned. The phenomenon was also noted by media sources in Sri Lanka in the 2004 Indian Ocean earthquake. It is possible that certain animals (e.g., elephants) may have heard the sounds of the tsunami as it approached the coast. The elephants' reaction was to move away from the approaching noise. By contrast, some humans went to the shore to investigate and many drowned as a result.

        Tsunami can be detected using our human senses. Recognize the tsunami’s natural warning signs.

Feel

• Strong local earthquake may cause tsunamis;
• Feel the ground shaking severely.

See

• As a tsunami approaches shorelines, water may recede from the coast, exposing the ocean floor, reefs and fishes.

Hear

• Abnormal ocean activity, a wall of water, and activity, a wall of water, and approaching tsunami create a loud «roaring» sounds similar to tat of a train or jet craft.

Run

• Don’t wait for official evacuation orders.
• Immediately leave low-lying coastal areas.
• Move inland to higher ground.
• Run if you see a tsunami coming.

IV. Conclusion

        So, what conclusions have I come to, while working on my project: we are advanced people living in the world full of modern technologies, so we should use all the possibilities which give us a chance to survive.

From my point of view, our great Earth has always reminded us to be humane and not to waste natural resources.

        I stand in silence for a minute to the departed souls in this great calamity world over.