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Tsunami Resources Hit Counter

•Definition & description
•Mechanisms
•Global occurrence
•Specific hazard
•Mitigation
•Case studies
 

 

 

 

 

 

 

 

 

 

 

 

Text Box: From ukiyo-e print by Hokusai c1830  The word Tsunami was coined by the Japanese and literally translates to "great wave in harbour"

 

 

 

 

 

 

A Tsunami is a series of large ocean waves generated by impulses from geophysical events (earthquakes, landslides and volcanic eruptions) on the ocean bottom or along the coastline.

 

 

 

Text Box: Tsunami of 1998 Papua New Guinea Pacific Tsunami Museum www.tsunami.org

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Tsunami Formation

•Mechanisms
•        Submarine faulting

Text Box: Tsunamis are usually caused by underwater earthquakes. These often occur offshore at subduction zones (places where a tectonic plate that carries an ocean is gradually slipping under a continental plate).

 

 

 

 

 

 

 

Text Box: Part of the sea floor can snap upward abruptly, while other areas sink downward, when sections of the plates that have been locked together for a while move suddenly under the strain.   In the instant after such an underwater earthquake, the shape of the sea surface mirrors the new contours of the sea floor--some areas of water are pushed upwards, and others sink.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Text Box: This starts a series of waves that rush outwards. These waves travel at more than 500 mph.   At first, out at sea in deep water, the waves are very far apart--sometimes hundreds of miles--and their crests are not very high, perhaps only a few feet above the rest of the surface (although these crests are only the tips of vast masses of water in motion).

Text Box: When a tsunami leaves deep water and approaches the shore, however, it slows down and its height grows.   The wave crests also squeeze closer together.

 

•Mechanisms
•    Submarine faulting

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Text Box: Region of vertical displacement following the 1964 Alaskan earthquake.   The region of uplift is approximated by an ellipse. Adapted from Plafker, (1965).

 

 

Text Box: Tsunami Hazards, Massey University, NZ http://geohazards.massey.ac.nz/tsunamis/intro_t.html

 

 

 

 

 

 

 

 

 

 

 

•Mechanisms
•    Volcanic eruptions & landslides

 

 

Krakatoa & Stromboli
 

 

 

 

 

        

 

•Mechanisms
•    Submarine landslides

 

Boxed area (enlarged below) shows a large submarine landslide off Santa Barbara, California.

This prominent slump is 14.6 km long by 10.5 km wide and extends from 90 m to a depth of 570 m

 

Submarine landslide hazards off Santa Barbara, California
www.mbari.org/news/news_releases/2000/dec15_greene.html