Tsunamis – Introduction

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Small Tsunami Wave[7]
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A tsunami is a naturally occurring series of waves in a body of water that results when a rapid, large-scale disturbance is caused by an earthquake, landslide, volcanic eruption, or an extra-terrestrial impact event.

Although a tsunami cannot be prevented, the impact of a tsunami can be mitigated through community preparedness, timely warnings, and effective response.[1]

Origins and History

The word tsunami is a Japanese word, represented by two characters 津波: tsu meaning “harbor” and nami meaning “wave”. As early as 426 BC, the Greek historian Thucydides, in his work History of the Peloponnesian War, inquired about the causes of tsunamis and was the first to argue that ocean earthquakes must be the cause.[2]

U.S. Tsunami Historical Record

The recorded tsunami history of the United States is quite short by world standards. In Washington, Oregon, and California, it is at best 180 years long, while a few older events are identifiable from paleotsunami studies.[3]

Since 1690, more than 200 tsunami events have affected the United States and its territories, causing 700 deaths and $300 million in economic loss.[4]

Traditionally, the East Coast of the United States has been thought of as an area that has been almost entirely free of tsunamis. Unlike the Pacific Ocean, the Atlantic Ocean is not surrounded by marked subduction zones where earthquakes with a relatively large vertical offsets are likely to occur. Classic thought about tsunamis has considered such subduction zone earthquakes to be the major generators of large tsunamis. However, in 1998 a Mw 7.1 earthquake occurred in Papua New Guinea, triggering an offshore landslide that generated a 15-meter tsunami. This tsunami resulted in about 2,200 deaths.[5]

One of the most notable earthquakes on the East Coast of North America occurred off the Burin Peninsula of Newfoundland in November 1929 caused much property damage and 29 deaths along the coast of Newfoundland. This 7.2 Ms earthquake caused a turbidity current that cut twelve transatlantic telegraph cables. It generated a local tsunami (perhaps a landslide-tsunami) that was recorded at Atlantic City, New Jersey, and Charleston , South Carolina, and possibly other places on the East Coast. The three to seven meter waves resulted in 29 deaths, but none of these fatalities were in the United States.[6]

 

References:

  1. NOAA – Tsunami: http://www.tsunami.noaa.gov/
  2. Thucydides: “A History of the Peloponnesian War”, 3.89.1–4
  3. FEMA – Tsunami Hazards: http://www.fema.gov/media-library-data/20130726-1541-20490-8257/frm_p1tsun.txt
  4. NOAA-NGDC (National Geophysical Data Center) – Tsunami Data Fact Sheet: http://www.ngdc.noaa.gov/hazard/data/publications/tsunami_fact_sheet.pdf
  5. NOAA-NGDC (National Geophysical Data Center) – Tsunamis and Tsunami-Like Waves of the Eastern United States: http://www.ngdc.noaa.gov/hazard/data/publications/ref0541_lockridge.pdf
  6. NOAA-NGDC (National Geophysical Data Center) – Tsunamis and Tsunami-Like Waves of the Eastern United States: http://www.ngdc.noaa.gov/hazard/data/publications/ref0541_lockridge.pdf
  7. Image Source: http://www.erh.noaa.gov/okx/tsunami.html [Accessed December 11, 2013]

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