Managing Volcanic Risk

Question 1

3 ps

Answer 1

Prediction, protection and preparation

Question 2

Geological observations: slope angle

Answer 2

. Measuring the topography (ground shape) of a region, ground movements that occur around a volcano when it is active
. Slope angle:
. A tiltmeter measures changes in the slope of a volcano’s side, tiltmeter is installed when volcano is inactive + no changes in topography
. The tilt measured this time is 0 degrees.
. When more magma rises into the magma chamber, the volcano as a whole expands.
. Slope change shown

Question 3

Geological observations: EDM + GPS

Answer 3

. Distance Measurements: Electronic Distance Measurements used to measure horzontal movements
. When the volcano expands before an eruption, this distance will increase and the change can be recorded
. GPS (Global Positioning System) is also used to measure horizontal changes
. Receivers that are placed all over the volcano receive signals from satellites
. By calculating their distance from the satellite, their location relative to one another can be determined
. Even small expansions of the volcano can be noted
. GPS lets scientists determine vertical movements

Question 4

Seismic activity

Answer 4

. Seismic activity always occur as volcanoes awaken
. Measured using local seismographs
. Researchers can detect volcanic eruptions by monitoring infra-sound
. The IMS Global Infrasound Network has 60 stations around the world that work to detect and locate erupting volcanoes
. As many volcanoes are found at/near plate boundaries it is difficult to observe whether seismic activity is related to the volcano or the general movement of the plates
. Accurate prediction is difficult

Question 5

Gas emissions

Answer 5

. As magma nears the surface and its pressure decreases, gases escape
. Increasing amounts of sulphur dioxide (1 of main comps of volcanic gases) show the arrival of increasing amounts of magma near the surface.
. On May 13, 1991, an increasing amount of sulphur dioxide was released from Mount Pinatubo in the Philippines
. On May 28, 2 weeks later, sulphur dioxide emissions increased to 5,000 tonnes, 10x earlier amount
. Mount Pinatubo later erupted on June 12, 1991
. Drop in gas levels caused by the sealing of gas passages by hardened magma - meaning increased pressure, eruption more likely

Question 6

Satay tips for eruptions

Answer 6

• Stay away from active volcanoes
• Keep goggles, mask, torch and battery operated radio in an emergency kit
• Know evacuation route, keep gas in car and stay below 35mph
• Avoid river areas and low lying regions
• Wear long trousers + sleeves
• Close windows, doors and block chimneys to prevent ash coming in, sweep ash away due to excess weight

Question 7

Lava control: bombing lava tubes

Answer 7

. Lava tubes are cooled and hardened outer crusts of lava which provide insulation for the faster-flowing, molten rock inside
. In theory, bombs would destroy the lava tubes, ruining transport channel + exposing lava to air cooling it
. But in practice, while bombs created craters in parts of the tubes, they were soon filled again by the lava

Question 8

Lava control: water

Answer 8

. Lava stops in the 1970s on Haimey (Iceland) - Lava from the Eldfell volcano threatened the island’s harbour and Vestmannaeyjar
. For almost five months in 1973, sea water was blasted through cannons towards the lava
. As water hit the superheated rock, it turned into steam, allowing the lava’s heat to dissipate
. 1.5 billion gallons of water used
. Conditions were right and lava was slow moving

Question 9

Lava control: build a barrier

Answer 9

. Mount Etna, in March 1983
. Barriers of rock and ash were constructed to divert the lava
. One of the first barriers, 18m high and 10m wide, was overrun, but a second barrier blocked lava from moving further west
. Two other major barriers kept the flow from reaching the main tourist area of Etna
. The lava missed buildings by metres

Question 10

Lava control: add concrete

Answer 10

. Mount Etna - early 1990s
. Workers created an artificial trench to catch lava redirected from a breach made with explosives
. Only pushed away part of the lava, so concrete blocks were dumped into the remaining flow, fully diverting its path.

Question 11

Lava diversion evaluation

Answer 11

. Diversion may push lava away from one area only to direct it toward another human settlement
. A better focus is improving the prediction of volcanic eruptions
. Give speople the best possible chance to move on their own terms