Hazard management- Monitoring and risk assessment

Question 1

In the 20th centtury, how many deaths were due to volcanic eruptions?

Answer 1

96,000

Question 2

What did 91% of the fatalities from volcanic eruptions in the 20th century result from?

Answer 2

Pyroclastic flows
Lahars
Tsunamis
Famine and epidemic disease

Question 3

What 3 things does short term forecasting and monitoring involve?

Answer 3

Volcano monitoring in real time
Eruption and forecasting and prediction
Volcanic emergency management and planning- local authorities, civil defense

Question 4

What 3 things does long term forecasting and monitoring involve?

Answer 4

Identify the high-risk volcanoes
Map and indentify past volcanic hazards to prepare for volcanic hazard
Long-term forecasts

Question 5

What does volcanic monitoring include?

Answer 5

Seismic monitoring
Ground deformation
Microgravity
Magnetic field
Volcanic gases
Temperature
Hydrology

Question 6

Why does volcanic monitoring include seismic monitoring?

Answer 6

Moving magma and gases cuases rocks to break- causing high frequency earthqaukes or low frequency earthqaukes/tremors

Question 7

What does short period/high frequency tremors suggest?

Answer 7

Fractures due to expansion of magma chamber

Question 8

What does harmonic (low frequency) tremors suggest?

Answer 8

Magma flows through feeder conduits (water/magma channels)

Question 9

What is a seismometer used for?

Answer 9

Used to record volcanic-related earthquakes
Tell us information about the tremors- timing, location, depth and magnitude

Question 10

What is ground deformation?

Answer 10

Changes to the surface of the volcano tells us what is happening below

Question 11

How do you measure ground deformation?

Answer 11

Requires precise surveying techniques
More accurate with recent advances in lasers

Question 12

How does geodetic levelling work?

Answer 12

Measures elevation differences between benchmarks (gps points)

Question 13

How does a tiltmeter work?

Answer 13

Precise levelling, displacements as small as 1-2cm can be determined

Question 14

How does an EDM (electronic distance meter) work?

Answer 14

Sends and recieves an electromagnetic signal to measure the distance when comparing the transmitted and received signal

Question 15

What is ground inflation?

Answer 15

Gradual changes in the volcano surface, and can occur over a period of months and years

Question 16

What is ground inflation?

Answer 16

Gradual changes in the volcano surface, and can occur over a period of months and years

Question 17

What is ground deflation?

Answer 17

Sudden change in the volcano surface, as the magma chamber is emptied associated with an eruption

Question 18

What does volcanic gas monitroring include?

Answer 18

Collecting ground samples
Taking airbourne measurements of eruption plumes
Analysis of water chemistry
(all for gas contents)

Question 19

What gas recordings help monitor gas explosions/releases from volcanic eruptions?

Answer 19

Sulfur dioxide (SO2)

Question 20

What does temperature (thermal) monitoring include?

Answer 20

Infrared imaging to detect and analyse active areas of a volcano
Can differentiate hot from cold eruptibe events
Highlights active faults

Question 21

What does hydrology monitoring include?

Answer 21

Monitoring sediment erosion, transport and deposition, water temperature, found vibrations (mudflows, lahars) and precipitation
As volcanoes interact with the local hydrology

Question 22

What assumption is made when analysing the risk/mapping volcanic hazards?

Answer 22

The geological past provides a useful guide to future activity

Question 23

What information is crucial to identifying and mapping volcanic hazards?

Answer 23

Careful stufy of geological record of volcanoes and their surroundings
Mapping distribution and extent of lava and pyroclastic flows
Dating events to help understand the frequency of eruptions- predict when they will next occur

Question 24

Why is it important to identify and map volcanic hazards?

Answer 24

Helps to plan for future events, know who needs to be evacuated- reducing deaths
Understanding the volcanic environment that has formed can inform where to build/not build
Combination of early warning systems can inform emergency managment agencies- best preparedness (all the info about the hazard) produce risk assessed cover map of landscape