TECTONICS - Plate boundary types
- Created by: aliceoliviaaa
- Created on: 24-04-18 14:36
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- Plate boundary types and their distribution
- Divergent
- Constructive
- displayed at mid-ocean ridges.
- The Mid Atlantic Ridge. Iceland Basaltic magma).
- shallow focus and low magnitude earthquakes (submarine [under the sea]). These generally do not trigger tsunamis.
- new dense oceanic crust is created by rising magma through the plates boundaries.
- Convergent
- Destructive-plates moving together
- active collision locations where plate material melts in the mantle, causing earthquakes and volcanoes.
- become really dangerous when one more-dense (oceanic) plate subducts below the other less-dense (continental) plate, causing a subduction zone with high levels of stress and friction.
- Earthquakes- Japan Tohoku tsunami 2011, and Aceh, Indonesia 2004.
- Volcanoes- magma fed by melting of subducting plate. (surface volcanism occurs in oceans directly above the down thrust plates.
- volcanoes associate with explosive events with a composite cone volcano.
- Volcanoes- magma fed by melting of subducting plate. (surface volcanism occurs in oceans directly above the down thrust plates.
- Between two continental plates, mountain ranges such as the Himalayas are formed
- Conservative
- The relative movement here is horizontal (Sinstrel [L] or Dextrel [R]).
- Oblique-slip, sliding or transform.
- The San Andreas Fault - Pacific Plate (north) creates friction against North American Plate (north at different speed).
- Lithosphere is neither created nor subducted and are the sites of extensive shallow focus earthquakes. No volcanic activity.
- Hot spot volcanoes are found in the middle of tectonic plates (anomalous volcanism).
- The Hawaiian Islands are an example of this occurring (pacific plate).
- Heat rises as a hot thermal plume from deep in the earth. High heat and low pressure at the base of the lithosphere enable melting of the magma. this rises through cracks.
- the hot spot stays static and as the plate moves away, forming sea mounts, atolls and islands. Volcanoes are rafted away and new ones form.
- Nearly all earthquakes are situated along the 'Pacific Ring of Fire' (70%)
- Volcanoes tend to be situated near plate boundaries
- intra-plate earthquakes
- Caused by man-induced activity such as fracking.
- Also caused by a weakness in the plate, a thermal plume or along a fault line.
- The Charleston earthquake, North Carolina, 1886.
- Divergent
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