Post on 13-Aug-2015
FACTORS AFFECTING THE IMPACT OF
VOLCANOES
Why some volcanoes are hazardous than the other?
• Type of Volcanic Eruptions• Type of Volcanic Materials Ejected• Geographical Location of a Place
Types of Volcanic Eruptions
EFFUSIVE ERUPTION EXPLOSIVE ERUPTION
Eruptions are quiet Non-explosive Spew basic lava that
spreads out over large areas
Less dangerous as people rarely get killed
E.g.: The Kilauea volcano in Hawaii.
Eruptions are loud & Violent
Explosive because of pressure building up in the magma
Eject acid lava, ash, gases & rock fragments
Dangerous as the materials can rain down on settlement
E.g. The Krakatau in Indonesia
LAVA FLOWS◦ Less dangerous to
humans◦ Travel slowly &
people are able to avoid them
◦ However, death may occur if the lava flows block people’s escape routes.
ASH –(smallest & finest fragments of lava or rock)◦ Ash in the air can
block sunlight & reduce visibility.
◦ Disrupt people’s activities.
◦ Cause asthma & coughs
Types of Volcanic Materials
VOLCANIC BOMBS◦ Large fragments of
volcanic rock. Semi-solid or partially molten
◦ Cause severe injuries & death to humans.
POISONOUS GASES◦ Trapped in magma are
released into the atmosphere when volcanoes erupt explosively
◦ Carbon Dioxide: can harm vegetation & air that has more CO2 can cause death in people & animals
◦ Sulphur Dioxide: contribute to the formation of acid rain. Causes skin, eye, nose & throat irritations.
PYROCLASTIC FLOWS◦ Gases mix with
volcanic materials◦ Fall down very quickly
down the slopes (up to 100km/h)
◦ Temp: 200 °C–700 °C◦ They will burn, knock
over or bury anything in their path
LAHAR (mudslide)◦ Occurs when water
mixes with ash & rock fragments.
◦ Flow very fast◦ Very destructive and
can bury anything in their path.
Volcanoes mostly located at plate boundaries◦ Countries that are in close proximity such as
Indonesia & Philippines will experience more impacts compare to Brunei.
The impact is greater if the volcanoes are located in close proximity to settlements.◦ Densely populated settlements will be at risk.
Geographical Location of a Place