A tsunami primer (1 of 6):
Tsunamis begin when the shape of the seafloor changes suddenly. The water above the changed seafloor is pushed up, but then because it is a fluid, immediately falls down to both sides, creating the wave that moves towards shore
Tsunamis begin when the shape of the seafloor changes suddenly. The water above the changed seafloor is pushed up, but then because it is a fluid, immediately falls down to both sides, creating the wave that moves towards shore
2 of 6: Tsunamis get taller when they approach shore. The whole column of seawater above a fault is moved, so there is a lot of water & energy in the wave, more if the sea is deeper at the source. As it approaches shore & depth of sea decreases, the height of the wave increases.
3 of 6: The 2 main causes of tsunamis are quakes on faults that push up seafloor & landslides. How big a tsunami is = how much water is displaced = how much seafloor moves up by how much. Only the biggest quakes (M≥8.5) move enough water to create a tsunami that crosses ocean
4 of 6: Strike-slip faults (faults that move the ground sideways, not vertically), like Jamaica, do not cause tsunamis b/c they do not change height of the seafloor. They can cause a local tsunami by triggering underwater landslides.
5 of 6: Tsunami waves move fast ~450 mi/hr. Faults near shore produce tsunamis that can arrive in a few minutes to 10s of minutes after you feel strong shaking. Time to go up hill. Tsunamis come in a series of waves that can last for a day. The first wave may not be the biggest
6 of 6: Today's Jamaican quake is strike-slip & did not produce a tsunami. Because there is no tsunami at the source, there cannot be a tsunami showing up somewhere else (like the US)
