ERTH 2415 Lecture 8: ERTH 2415_ Lecture 8
8 Feb 2019
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Document Summary
Tsunami"s get their source of energy from the earth"s internal energy. However, they may also be fuelled by gravity, and impact energy. Know what natural phenomena causes a tsunami. Know the characteristics of tsunami waves, and their difference from wind- caused waves. Tsunamis are ocean waves that are created due to underwater disturbances on the seafloor. Large earthquakes (magnitude >= 7. 5) usually trigger them. The trigger is a linear source: the fault on the seafloor. Energy is released perpendicular to the fault. Little attenuation: therefore there is potential for damage far away from the source. In fact, the wave amplitude increases near the shore. Vertical motion caused at the fault acts as a piston and creates an underwater disturbance. Volcanic eruptions, mass movements, impacts with space bodies can also cause them, but it is uncommon. Higher attenuation (therefore it has potential for local damage, but not far away from the source) Amplitude: max value measured from the equilibrium (max height)
