Hazards associated with volcanic eruptions

Question 1

hazards definition

Answer 1

only events that pose a threat to human life

Question 2

volcanoes definition

Answer 2

vents in the earth’s crust through which molten magma and gases erupt

Question 3

How are volcanoes distributed?

Answer 3

• on tectonic plate boundaries
• not found on constructive margins
• follow linear patterns

Question 4

Lava flows (description and impacts)

Answer 4

PRIMARY IMAPCT-layers of molten lava can destroy almost everything in their path…threaten whole settlements.
Impacts- rarely life threatening but can bury settlements, crops and land under tens of metres of volcanic rock. makes rebuilding/repair impossible

Question 5

Pyroclastic flows (description and impacts)

Answer 5

PRIMARY IMPACT-fast moving clouds of fragmented material varying from bombs and blocks to ash mixed with hot gases. can be referred to as ‘nue’e ardente/glowing cloud’
Impacts-death/injury and animals. burns and inhalation of poisonous gases

Question 6

Tephra (description and impacts)

Answer 6

PRIMARY IMPACT-solid material varying in size which is expelled into the atmosphere e.g. volcanic bombs
impacts- disrupts economic activity. makes airport runways impossible. roofs collapse, farmland is smothered and vehicles and jet engines malfunction

Question 7

Lahars (description and impacts)

Answer 7

SECONDARY IMPACT-volcanic mud flows caused by the ash erupting from the volcano mixing with river water
impacts-can transport rock debris more than 10m in diameter. causes economic and environmental damage. buildings and land are covered in thick layers of rock debris, can continue for many years

Question 8

volcanic gases (description and impacts)

Answer 8

PRIMARY IMPACT-volcanoes emit a variety of dangerous gases. hydrogen sulphide is most noticable, but also carhon dioxide, carbon monoxide, sulphur dioxide and chlorine
impacts-carbon dioxide killed 1700 people in Cameroon (1986)

Question 9

tsunami (description and impacts)

Answer 9

SECONDARY IMPACT-oversized wave in sea or lake triggered by the collapse of volcano flanks or caldera-formity volcanic events
impacts-created santorini caldera that is believed to have wiped out 80% of the Minoan people at the time of great civilisation

Question 10

climate change (description and impacts)

Answer 10

SECONDARY IMPACT-large volumes of ash and gas ejected into the atmosphere can reduce global temperature by blocking out sunlight
impacts-the 1783 Laki eruption had a global impact that reduced crop yeild; in 1991 the eruption of mount pinatubo led to a 0.5 degree fall in mean temperature globally

Question 11

landslides (description and impacts)

Answer 11

SECONDARY IMPACT-collapse of volcano flanks as eruptions take place
impacts-eruption of mount st.helens in 1980n triggered the largest landslide ever witnessed

Question 12

flooding (description and impacts)

Answer 12

SECONDARY IMPACT-melting glaciers/ice caps can release huge quantities of water in short periods
impacts-mount st helens (1980) and grimsvotn, iceland (1996)