Estuary Processes and Managment - River Dynamics and Integrated River Management - page 476

inundated Hilo on the island of Hawai'i with a 14 m high surge. The 2004 Indian Ocean earthquake was
an undersea earthquake (With a magnitude of between 9.1 and 9.3) that occurred at 00:58:53 UTC Dec.
26, 2004, with an epicentre off the west coast of Sumatra, Indonesia. The earthquake triggered a series of
devastating tsunamis along the coasts of most landmasses bordering the Indian Ocean. The disaster,
known as the Asian Tsunami or Boxing Day Tsunami, caused approx. 350,000 deaths and many more
injuries (http://en.wikipedia.org/wiki/Tsunami), and inundation of coastal communities with waves up to
30 m. It was one of the deadliest natural disasters in history. Indonesia, Sri Lanka, India, and Thailand
were hardest hit.
Mitigation of tsunami disasters relies mainly on early warning, disaster preparedness, vulnerability
reduction and post-disaster relief and reconstruction (See http://lareef. blogspot.com/). There were no
tsunami warning systems in the Indian Ocean to detect tsunamis or to warn the general populace living
around the ocean. Tsunami detection is not easy because while a tsunami is in deep water it has little
height and a network of sensors is needed to detect it. In the aftermath of the disaster, there is now an
awareness of the need for a tsunami warning system for the Indian Ocean. The United Nations started
working on an Indian Ocean Tsunami Warning System in 2005 (2004 Indian Ocean earthquake,
http://en.wikipedia.org/).
The first warning sign of a possible tsunami is the earthquake itself. However, tsunami can strike
thousands of kilometres away where the earthquake is only felt weakly or not at all. Because tsunami
consists of a trough and a peak and the trough causes "drawback", in the minutes preceding a tsunami strike,
the sea often recedes temporarily from the coast. Around the Indian Ocean, this rare sight reportedly
induced people, especially children, to visit the coast to investigate and collect stranded fish on as much as
2.5 km of exposed beach, with fatal results. On Maikhao beach in northern Phuket, Thailand, a 10-year-old
British tourist named Tilly Smith had studied tsunami in geography class at school and recognised the
warning signs of the receding ocean and frothing bubbles. She and her parents warned others on the
beach and saved many people. John Chroston, a biology teacher from Scotland, also recognised the signs
at Kamala Bay north of Phuket, taking a busload of vacationers and locals to safety on higher ground
(http://en.wikipedia.org/).
Hurricane —A hurricane is a type of tropical cyclone, which is a generic term for a low pressure
system that generally forms in the tropics. The cyclone is accompanied by thunderstorms and, in the
Northern Hemisphere, a counterclockwise circulation of winds near the earth's surface with a maximum
speed about 120 km/h. Each year, about eleven tropical storms develop over the Atlantic Ocean, Caribbean
Sea, and Gulf of Mexico and six of them become hurricanes. Hurricanes are categorized according to the
strength of their winds using the Saffir-Simpson Hurricane Scale. A Category 1 storm has the lowest wind
speed, while a Category 5 hurricane has the strongest. Hurricane and tropical storms produce significant
damage and loss of life, mainly due to flooding (Source: http://www.nhc.noaa.gov/).
When the winds from these storms reach 63 km per hour, the cyclones are given names. An
international committee developed names for Atlantic cyclones. In 1979 a six year rotating list of Atlantic
storm names was adopted - alternating between male and female hurricane names. Storm names are used
to facilitate geographic referencing, for warning services, for legal issues, and to reduce confusion when
two or more tropical cyclones occur at the same time. Names are retired usually when hurricanes result
in substantial damage or death or for other special circumstances.
The year 2005 is a year of hurricanes, in which 26 tropical storms occurred, 12 more than 2004 and the
most for any year since records began in 1928. Fourteen of them reached hurricane strength and three of
those made it to category 5. And hurricane Dennis, Emily, Rita, Katrina and Wilma destroyed lives,
demolished houses and wrecked the land. They also smashed records. They were among the angriest,
most violent hurricanes ever to rip their way across the North Atlantic and batter the Caribbean and the