Volcanic hazards

Question 1

What is the spatial distribution of volcanoes?

Answer 1

Mostly on convergent plate boundaries; the Pacific, East Africa, western North and South America, eastern Russia, the Mid Atlantic Ridge

Question 2

How can eruptions be predicted?

Answer 2

• Detecting movement
• Seeing when the last one was and estimating
• Seismic sensors
• Gas release
• Infrasound
• Iceland Meteorological Office (IMO)

Question 3

What is the VEI?

Answer 3

Volcanic Explosivity Index

Measures the magnitude of a volcanic explosion.

Question 4

What does the VEI use to measure eruptions?

Answer 4

• Volume of ejecta
• Height of eruptive column
• Qualitive descriptions
• Past activity
• Height of spreading of eruptive plume head

Question 5

What affects an explosion?

Answer 5

• Pressure
• Plate boundary its on
• Frequency

Question 6

What are the 3 diff. types of magma?

Answer 6

• Basaltic = least viscosity, acidity and explosivity
• Andesitic = medium
• Rhyolitic = most viscosity, acidity and explosivity

Question 7

What does the eruptions of Kilauea vs. Yellowstone show about how the size of eruption impacts frequency?

Answer 7

The bigger the eruption, the more infrequent eruptions are.
Kilauea erupts every few months. Its eruptions are 0.01-0.1 cubic km.
Yellowstone erupts every 100,0000 yrs and has an eruption of >1000 cubic km.

Question 8

What is tephra?

Answer 8

Solid material of varying grain size ranging from volcanic bombs to ash ejected into the atmos.
AKA pyroclastic fallout.

Question 9

What is pyroclastic flow?

Answer 9

Super heated (over 800 degrees) gas, ash and volcanic rock that flows down the side of the volcano. Travels at high speed (80kmph) and travels a long way (10-15km).
Also know as nuees ardentes.

Question 10

What are lahars?

Answer 10

Melted snow and ice as a result of the eruption combined w/ volcanic ash forms mud flows. These flow very quickly and travel 10s of kms.
They can bury or destroy natural habitats, settlements and infrastructure.

Question 11

What are Jokulhaups?

Answer 11

When an eruption melts glaciers and ice caps and causes flooding.

Question 12

What are tsunamis?

Answer 12

Sea waves generated by violent eruptions.

Question 13

How is acidic rain formed from eruptions?

Answer 13

Volcanic gases can react w/ water vapour in the atmos. which then falls as acid rain. E.g. Sulphur dioxide reacts w/ water to form weak sulphuric acid. Damages ecosystems and causes metal and stone to deteriorate.

Question 14

What are some of the volcanic gases?

Answer 14

Carbon dioxide
Carbon monoxide
Hydrogen sulphur
Sulphur dioxide
Chlorine

They can be harmful to humans and animals.

Question 15

What is a lava flow?

Answer 15

Lava flowing from a vent in the side of the volcano. Speed and distance travelled depend on temp. and viscosity. Low viscosity may travel 10kmph and flow a long way. Most are slow so ppl have time to evacuate but lava flows destroy everything in there path.

Question 16

What are some of the social impacts of volcanic hazards?

Answer 16

• Ppl killed, buildings and infrastructure destroyed by pyroclastic flow and fallout (primary)
• Pyroclastic flows and lava start fires (primary)
• Mudflows and flooding from ice melts can cause further damage and deaths (secondary)

Question 17

What are some of the economic impacts of volcanic hazards?

Answer 17

• Businesses destroyed and aircraft prevented from taking off due to ash cloud - damages economy of region and country, possibly international (secondary)
• Damage to building and infrastructure expensive (secondary)
• Stop tourism which can damage economy but could also encourage tourism due to the nice scenery created (secondary)

Question 18

What are some of the environmental impacts of volcanic hazards?

Answer 18

• Ecosystems destroyed by flows and fallout (primary)
• Acid rain, damages aquatic ecosystems and leaves on trees and removes nutrients from soil (secondary)
• Enhanced greenhouse effect (secondary)
• Reduction of sunlight reaching earth so reduced temp.s (secondary)

Question 19

What are some of the political impacts of volcanic hazards?

Answer 19

• Damaged agricultural land = food shortages = conflict and political unrest (secondary)
• Gov. spend money on repairing damage, may hinder dev. of country (secondary)

Question 20

What are short term responses to volcanic hazards?

Answer 20

Happen before, during or after.

E.g. evacuating ppl and providing emergency food

Question 21

What are the 3 categories of long term responses?

Answer 21

Prevention - e.g. stop dev. on land around volcano

Preparedness - e.g. authorities can monitor, ind.s can prepare w/ emergency kit and plan etc.

Adaptation - e.g. buildings strengthened so they don’t collapse