ERTH 2415 Lecture 8: ERTH 2415 - CLASS 8
5 Oct 2016
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Document Summary
A tsunami is a natural hazard fuelled by the earth"s internal energy but it can also be fuelled by gravity and impact energy. Tsunami: an ocean wave most often created by underwater disturbances of the seafloor. It is mostly triggered by large earthquakes (magnitude of 7. 5 or higher). It is less commonly by volcanic eruptions, mass movements, and impacts with space bodies: earthquake-caused tsunami (trigger is a linear source fault on seafloor) Energy released in a preferential direction (perpendicular to fault) Little attenuation (potential for damage far away from source) Verticle motion of rock blocks on the seafloor vertical motion acts as piston and wave amplitude increases near the shore a: volcano- and landslide-caused tsunami (trigger is a point source) Geographical occurences pacific ocean is surrounded by active volcanos and subduction zones. 80% of the world"s earthquakes are around the pacific ocean. Wave characteristics include: amplitude, wavelength, direction of propagation, and velocity of propagation.
