4.1 Volcano Hazards

Question 1

Types of magma

Answer 1

Viscous

Non viscous

Question 2

What are the features of viscous magma in volcanoes

Answer 2

Composition - silicic and intermediate
Explosive eruption
Hazards - pyroclastic flows, volcanic ash, lahars

Question 3

Features of non-viscous magma in volcanoes

Answer 3

Composition - mafic
Passive eruption
Hazards - lave flows, volcanic gases or vog

Question 4

Non viscous magma example

Answer 4

Mt Kilaunea hawaii 2018
Slow moving lava flows allowing gas to escape
Road closures and warnings to people
Burning everything in its path
Fire fountains from bubbling lava at fissures as gas escapes
Vog - water vapour plus volcanic gas make toxic smoke
Vog - direction uncontrolled, people downwind from fissure warned to limit exposure

Question 5

Viscous magma example

Answer 5

Mount Fuego, Guatemala 2018
1. Pyroclastic flow: hot rocks, ash, gas at high speed (200km/h) away from volcano
2. Methods of formation
A) Mushroom cloud with eruption column, can collapse to create pyroclastic flow
B) Lava dome with viscous magma. Dome collapses, gases expand causing pyroclastic flow
C) Volcanic ash (tephra) bury buildings and people, respiration problems

Question 6

How do you predict a volcanic eruption

Answer 6

Thermal anomalies
Ground deformation
Seismic monitoring
Gas emissions