Hazards Produced By Explosive/effusive Eruptions

Question 1

Lava flows

Answer 1

Typically happen with basaltic lava because it is free flowing

Acidic lava like rhyolite are thick so they do not flow easily

They rarely cause injuries/deaths

EXAMPLE: in Hawaii in 2015, a lava flow extended for 20 km and later in the year, another lava flow covered 800 m in one day

Question 2

Pyroclastic flows

Answer 2

A combination of gases that are 500 degrees or hotter, ash and rock fragments travelling at high speeds (100 km/h)

Question 3

Tephra

Answer 3

Any material ejected from the volcano into the air. Ranges in size from fine ash to volcanic bombs (6 cm)

Potentially hazardous because is can bury farmland in layers of ash

2010 Icelandic volcano led to the cancellation of 100 000 flights

Question 4

Toxic gases

Answer 4

CO, CO2 and SO2 pose a large threat to resident populations

When SO2 combines with atmospheric water, rain becomes acidic which damages crops

Question 5

Lahars. Give an example

Answer 5

Mud flows which form when ice on top of a volcano is rapidly melted and mixes with rock, ash and soil

EXAMPLE: 1984 eruption of Nevado del Ruiz caused multiple lahars which killed 23 000

Question 6

Floods

Answer 6

Volcanic eruptions beneath a glacier can cause rapid melting

EXAMPLE: in iceland, many volcanoes lie under the Vatnajökull icefeild causing flooding