From Ocean Teacher Library
Tsunami Science and HazardContents |
Tsunamis have physical characteristics that are very different from ocean swells
and surfing waves. The videos show examples of actual tsunamis on December
26, 2004 that struck the coasts of Indonesia 30 to 45 minutes after the
earthquake, and the coast of Thailand ~3 hours. Television news in Banda
Aceh, Sumatra, Indonesia, and tourists vacationing at Patong Beach, Thailand
captured vivid images of the tsunami’s arrival and devastation.
The first arrivals are seen in Thailand as a thunderous wall of water that
immediately floods inland. The wave forces and currents are so strong and
turbid that people can easily be swept off their feet where they can drown
quickly or be thrown against buildings or trees and lose consciousness. As
successive waves enter a city or village, streets can become river channels for
floating debris.
Tsunami waves can arrive for hours, with each receding wave pulling debris out
to sea, followed by an advancing wave that picks up the same debris and more,
and re-deposits it inland. Floating debris become, in essence, battering rams
causing more damage as they strike whatever is in their way. Each wave
scours and erodes coastlines and building foundations, but also deposits a layer
of sand and mud when it hits shore. Secondary impacts caused by wave
breakage include fires and HAZMAT spills when power, utility, or resource lines
are severed. In 1993 in Okushiri, Japan, fires broke out when gas lines broke
during the onslaught of tsunami waves. While many heeded natural warning
signs and siren alerts and evacuated that evening, fire razed the homes of many
citizens in the lowland town of Aonae, Japan.
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Short title: Tsunami Science and Hazard
Description: This page contains information on Tsunami Science and Hazard.
Expertise level: beginner
Author: Tammyfukuji
Approval status: approved
Approved by: Tammyfukuji
Last change: 2011-4-7
Subsection of: Strengthening Tsunami Warning and Emergency Response
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