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Distribution of tectonic hazards (Convection currents (There is a…
Distribution of tectonic hazards
Types of Hazards
Tectonic hazards
= a natural event caused by internal earth processes, e.g. plate movements that have the potential to cause loss of life or damage to property.
Seismic hazard
= generated when rock falls within 700km of the earth’s surface and comes under stress that they break or becomes displaced.
Volcanic hazards
= those associated with eruption events at the earth’s surface.
Primary hazards
= immediate - earthquakes, volcanoes.
Secondary hazards
= Produced later - tsunamis, landslides.
Earthquakes
Earthquakes are mostly scattered and grouped on plate margins, but some are not, for example, many earthquakes occur on the plates such as the Eurasian plate and also in Hawaii.
Intra-plate
Volcanoes are distant from a plate boundary at locations called mid-plate hotspots.
Convection currents
There is a destructive plate boundary at the trenches at the side of the currents
There is a constructive plate boundary at the top of the convection current
Core = radioactive decay occurs here and it causes extreme temperatures in the mantle
It is between 0-100km
The crust is made up of solid rock (basalt, granite)
The earth’s crust is made up of a big jigsaw puzzle: 7 big slabs and many other little ones.
Mantle Plumes
These rise towards the surface generating basaltic volcanoes that tend to erupt continually. This is stationary, but the tectonic plate moves slowly over it. Over millennia, this produces a chain of volcanic islands, with extinct ones most distant from the plume location.
Volcanoes
Volcanoes are also mostly scattered on plate margins. However, there are some anomalies in places again such as Hawaii, for example, Kilauea and Mauna Loa on the Pacific plate. There is a cluster of volcanic eruptions along the Eurasian plate.
