Geophysical Hazards
Mechanisms of plate movement:
Internal heating
Convection currents
Plumes
Subduction
Rifting at plate margins
Internal Structure of the Earth:
The solid mantle makes up 82% of the volume of the Earth.
The density of the layers is controlled by temperature and pressure.
Internal Heating:
The flow of heat comes from two main sources-radiogenic heat (radioactive decay of
materials in the mantle and crust) and primordial heat (heat lost by the Earth as it continues to
cool from its original formation).
Earth heat is transferred by convection, conduction and volcanic advection.
o Most is by mantle convection, with the remaining heat mainly originating in the
Earth's crust
o About 1% is due to volcanic activity, earthquakes and mountain building.
o Almost all of the Earth's internal heat loss at the surface is by conduction through
the crust.
Mechanisms of plate movement:
Internal heating
Convection currents
Plumes
Subduction
Rifting at plate margins
Internal Structure of the Earth:
The solid mantle makes up 82% of the volume of the Earth.
The density of the layers is controlled by temperature and pressure.
Internal Heating:
The flow of heat comes from two main sources-radiogenic heat (radioactive decay of
materials in the mantle and crust) and primordial heat (heat lost by the Earth as it continues to
cool from its original formation).
Earth heat is transferred by convection, conduction and volcanic advection.
o Most is by mantle convection, with the remaining heat mainly originating in the
Earth's crust
o About 1% is due to volcanic activity, earthquakes and mountain building.
o Almost all of the Earth's internal heat loss at the surface is by conduction through
the crust.
