Disaster Risk Management

Disaster Risk Management

Indian Ocean Tsunami

The devastating tsunami in the Indian Ocean of December 26, 2004, alerted the world to one of the most terrifying natural phenomena on Earth. Few will forget the scenes of carnage and destruction wrought by the floodwaters as they swept across coastal areas. In fact, tsunamis have been known about for generations. The word tsunami is derived from the Japanese word meaning “harbor wave.” Tsunamis are frequently described like tidal waves; however, this view is erroneous, since they have nothing to do with tides. Tsunami is generated by offshore earthquakes, submarine slides, and, occasionally, sub aerial landslides that enter water bodies. Asteroid impact is an additional but much rarer mechanism. With the exception of asteroid impacts, the displacement of mass, whether through submarine sediment slides, the collapse of a volcanic edifice, or an earthquake that induces faulting of the seabed, leads to a large-scale displacement of water. Although most tsunamis are phenomena associated with the open ocean, some tsunamis can be generated within lakes and/or fjords due to rock slide failures. An attempt is made here to explain the processes of tsunami generation and propagation as well as what happens when tsunamis strike coastlines. A description is also given of how societies have responded to the perception of tsunami risk (Chini & Bignami, 2008).

In the case of the 2004 Indian Ocean tsunami, since the Pacific tsunami warning system did not extend like far afield like Indonesia, it was not possible to generate an instant warning to countries bordering the Indian Ocean. Instead, the first indications that tsunamis were likely to be generated came from the global array of seismic monitoring stations that were recording the occurrence of a huge earthquake beneath the Indian Ocean.

The presence of a tsunami warning system is essential for the Pacific region due to the large number of tsunamis that are known to have occurred. However, large tsunami is also known to have taken place in other parts of the world, albeit less frequently. The Indian Ocean tsunamis of 2004 are a good example of this, but there have been many other catastrophic events. In Europe, for example, the most destructive historical tsunamis were those that accompanied the Lisbon earthquake of November 1, 1755; the earthquakes in Sicily and Calabria on February 5, 1783, and December 8, 1908, respectively; and the Aegean Sea earthquake of July 9, 1956. Of these, the most destructive event was the Lisbon earthquake in 1755.

In the less wealthy parts of the globe people tend to be relatively directly dependent on the natural environment. Their resilience is mostly locally determined, and buffers against hazards are thin in terms of time, as well as economic and material resources. For example, when powerful storms such as Typhoon Chataan strike a less wealthy and nonindustrial place such as the Federated States of Micronesia (FSM), there is typically less warning, less locally based technology for emergency response, and less wealth to support nutrition and ...