The Range of Physical Phenomena that are Associated with Volcanic Hazards

The Range of Physical Phenomena that are Associated with Volcanic Hazards

Volcanic eruptions bring with them a large range of hazards. This

report will describe the different range of hazards associated with

volcanic activity and discus possible ways that hazards can be

avoided. A volcanic eruption can, force people to leave their homes,

damage sources of water, destroy homes and farms, restrict travel and

kill.

Pyroclastic flow is a flow of volcanic rock, and the most devastating

effect of an explosive eruption. A pyroclastic eruption is one in

which the great majority of activity involves fountaining or

explosions. Nothing from a volcano is as blistering hot and moves with

as much power and speed as a pyroclastic flow. A pyroclastic flow

starts with rocks and gasses being shot up to 20 miles high into a

mushroom shaped cloud. Later the column collapses and rocks and hot

ash avalanche down the mountain. The rocks have the effect of running

water as they it suffocates everything in its way. Large boulders are

carried down the volcano as smaller rocks turn and act like a conveyor

belt under them. It was a pyroclastic flow that destroyed Pompeii and

killed thousands in 79AD.

Pyroclastic flows are nothing like the slow predictable movement of

lava. Molten rock creeps along the surface but very rarely takes lives

as it is easily outrun. Lava flows have a devastating effect on houses

and other structures as it can destroy these very easily.

Heavy ash fall spat out by the volcano can make breathing hard and

flatten houses. The ash is especially more dangerous if wet. Volcanic

ash is material thrown out of a volcano as particles, and less than

2mm across. Ash can damage crops or force an area to be abandoned.

Earthquakes can be associated with volcanic activity but they are

usually small and shallow. Volcanic earthquakes are almost always due

to the movement of magma. When a volcano starts to show some unrest

the earthquakes tend to be deep. As the magma batch moves to the