Volcanic Hazards Lab

Types of volcanoes

• Shield

• Cone

• Caldera

• Volcanic field

Volcano compositions

• basaltic

• andesite

• rhyolitic

Viscocity

Measure of how easily substance flows - dependent on composition, temperature and gas content of magma

Shape of volcano

Determined by viscocity of magma and eruptive process

Basaltic

• low silica

• low viscocity

• form shield volcanoes and scoria cones

Andesite

• intermediate silica

• intemediate viscocity

• form cone volcanoes or composite cones

Ryholite

• high silica

• high viscocity + gas charged

• form calderas

Basaltic eruption types, products & sources

• lava flows

• tephra

• volcanic gases

• debris avalanches

Andesite eruption types, products & sources

• lava flows

• tephra

• volcanic gases

• pyroclastic flows

• pyroclastic surges

• debris flow

• debris avalanches

Rhyolite eruption types, products and sources

• pyroclastic flows

• pyroclastic surges

• lateral blasts

• tephra

• lava domes

• lava flows

• volcanic gases

• debris avalanches

Pyroclastic fall

vertical eruption column of material that dispenses in downwind direction

Pyroclastic flows

suspension of ash, gases, crystals and rock material

can be >500^oC and move up to 300m/s

Tephra

medium-fine grained volcanic material generated during an eruption which forms an eruption column

lava flows

outpouring of molten rock

slow moving

lahars

fast moving masses of water and volcanic mud and debris

debris flow

landslide on the flank of a volcano, occur when part of a volcano becomes unstable and fails

volcanic gases

produced during eruptions, toxic and can be silently destructive