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PLATE TECTONICS (convection currents within the mantle (DIVERGENT heated…
PLATE TECTONICS
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VOLCANOES primarily found at plate boundaries, uprising of magma through cracks and fissures
stratovolcano
convergent plate boundaries, subducted and melted plate has high silica content, viscous lava that traps gases easily, more violent eruptions
highly explosive eruptions: pyroclastic flow, lahars, landslides, air pollution
shield volcano
divergent plate boundaries, lava risen from mantle has low silica content, less viscous, gases can escape easily, less explosive eruptions
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benefits
fertile soil - minerals that otherwise can only be extracted after millions of years when the rocks have been eroded ; especially important to countries that depend heavily on agriculture
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geothermal energy; requires technology and financial capacity, only in DCs
MEASURES
preparedness - largely dependent on financial capacity of the country and adequate knowledge among citizens
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EARTHQUAKES (LOCALISED) sudden release of stored energy in rocks found along fault lines in the form of seismic waves - unexpected, little time for preparations
TSUNAMIS (REGIONAL) - underwater, offshore earthquakes, underwater volcanic eruption, landslide ; columns of water displaced, travelling in all directions as waves
however, the extent of explosiveness can be determined by the amount of built-up pressure in the volcano as well eg. Iceland volcano 2010
on reaching shallower water, greater friction slows down the waves and thus they increase in height
- population density
- level of preparedness
- distance from epicentre
- level of development
- magnitude
- type of soil
- time of occcurrence
- depth of focus #