EARTHSC 2GG3 Lecture 4: lecture 4

• School: McMaster University
• Department: Earth Sciences
• Course: EARTHSC 2GG3
• Professor: Mark Moscicki

Document Summary

Tsunamis: tsunami is japa(cid:374)ese for (cid:862)har(cid:271)our (cid:449)a(cid:448)e(cid:863), they are produced by the sudden displacement of water, events capable of triggering tsunamis, earthquakes that cause uplift of the seafloor, landslides, volcano flank collapse, submarine volcanic eruptions, meteorites. Earthquakes can cause tsunamis in two ways: by displacement of the seafloor, by triggering a landslide that enters water. Generally, an earthquake must be at least m 7. 5 to trigger a tsunami. Tsunamis develop in a 4-stage process: stage 1: displacement of the seafloor sets waves in motion that transmit energy outward and upward. When the waves reach the surface of the water, they spread outward: stage 2: in the deep ocean, the waves move rapidly (they can reach speeds of over 500 km/h). The spacing of the wave crests is very large (it can be more than 100km). The height (amplitude) of the waves is often small (less than 1 m).