TECTONICS - Causes of tsunamis and volcanoes
- Created by: aliceoliviaaa
- Created on: 26-04-18 11:44
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- Causes of volcanoes and tsunami's
- volcanoes
- Secondary hazards include lava flows, pyroclastic flows, ash falls, gas eruptions, lahars and jokulhlaups.
- occur at destructive plate margins.
- composite cone volcanoes threaten the most danger, whereby areas up to 30km away may be affected.
- Tsunamis
- Can be generated by landslides and even eruptions on volcanic islands. most are generated by sub-marine earthquakes at subduction zones.
- A vertical displacement of the sea bed (up or down) called slab-pull, at a subduction zone. This displaces a large volume of water.
- Characteristics of tsunami waves in deep ocean:
- wave heights less than 1m.
- wave lengths of more than 100km.
- speeds of 500-950 km/h.
- As they approach the shore:
- slow dramatically, wavelength drop and wave height increases.
- May hit the shore in a series (wave-train).
- the 2004 Indian Ocean Tsunami
- killed 230,000–280,000 people.
- The undersea megathrust earthquake was caused when the Indian Plate subducted beneath the Burma Plate.
- a moment magnitude (MMI) of 9.1–9.3 and a maximum Mercalli intensity of IX (Violent).
- Can be generated by landslides and even eruptions on volcanic islands. most are generated by sub-marine earthquakes at subduction zones.
- volcanoes
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