Prediction and monitoring

Question 1

Can people predict volcanoes?

Answer 1

People are still not capable of predicting exactly when and where volcanoes will occur.

Question 2

How can locations and time frames where volcanoes will occur be narrowed down?

Answer 2

By large scale monitoring of tectonic activity

Question 3

How is tectonic activity monitored?

Answer 3

By studying the geographic area of the volcano

• earthquake activity
• monitoring gas emissions
• ground deformation
• thermal monitoring
• satellite images and remote sensing
• mass movements and mass failures

Question 4

How do scientists study the geographical area?

Answer 4

They use seismic waves to show if a vulcano is getting ready to erupt. Many volcanoes experience an increasing intensity in frequency and size of earthquakes as they prepare to erupt

Question 5

What are other key signs that a volcano is going to erupt?

Answer 5

The types of earthquakes that occur and where they start and end

Question 6

How can people monitor this?

Answer 6

Using seismometers which produce seismographs

Question 7

How many seismic forms does volcanic seismicity have?

Answer 7

Volcanic seismicity has three major forms: short period earthquake, long period earthquake and harmonic trmor

Question 8

What are short-period earthquakes?

Answer 8

Are like normal fault-generated earthquakes. they are caused by the breaking and fracturing of brittle rock as magma forces its way upward

Question 9

What are long-period earthquakes?

Answer 9

They indicate increased gas pressure in a volcano’s plumbing system

Question 10

What are harmonic tremors?

Answer 10

They are often the result of magma pushing against the overlying rock beneath the surface. They can sometimes be strong enough to be felt as humming or buzzing by people and animals, hence the name

Question 11

Where the study of using harmonic tremors technique first used?

Answer 11

This technique was used in Nevado Del Ruiz in 1985 and for Mount Pinatubo in 1991 to predict when they would roughly erupt

Question 12

How can any earthquake activity be viewed regarding the volcano?

Answer 12

Any earthquake activity can be viewed as the volcano preparing for an eruption

Question 13

What does earthquake activity lead to?

Answer 13

The magma chamber will be getting full and the pressure inside the chamber material and gases will cause the rock around the volcano to be stretched and at breaking point

Question 14

Monitoring gas emissions

Answer 14

As Magma rises into magma chambers gases escape for the depressurising magma.

Question 15

What is one of the main gases

Answer 15

One of the main gases is Sulphur Dioxide, and if its quantity in escaping volcanic gas increases this can signal the start of a major eruptive sequence.

Question 16

What happened in the In the Mount Pinatubo Volcanic event in 1991?

Answer 16

In the Mount Pinatubo Volcanic event the amount of Sulphur Dioxide increased by 10 times in 2 weeks.

Question 17

What happens directly before eruption?

Answer 17

Directly before eruptions the Sulphur Dioxide level can then drop rapidly and scientists think this is due to the sealing of gas passages by hardened magma. This increases pressure in the volcano and leads to explosive eruptions.

Question 18

What is ground deformation?

Answer 18

The movement of magma within the lithosphere can deform the ground above, this has been witnessed at Yellowstone beneath Yellowstone Lake.

This swelling of the volcano signals that magma has collected near the surface. Scientists monitoring an active volcano will often measure the tilt of the slope and track changes in the rate of swelling.

Question 19

Which mountain showed ground deformation prior to eruption?

Answer 19

Mount St Helens showed this prior to its eruption in 1980.

Question 20

What is thermal monitoring?

Answer 20

Both magma movement,
changes in gas release
and hydrothermal activity can lead to thermal emissivity changes at the volcano’s surface.

We can use satellite imagery, activity of minor extrusive features such as geysers and hot springs and mapping to monitor this.

Question 21

What are Satellite Images and Remote Sensing?

Answer 21

Remote sensing is the use of satellites to detect things about the Earth’s surface. This is useful for monitoring any changes in volcanoes at the surface.

Using satellites scientists can monitor the thermal activity of the volcano to check for upwelling magma

Question 22

What is checked with remote sensing with satellites?

Answer 22

Checks for escaping Sulphur dioxide using gas sensing.

Checks to see if the ground is deforming by checking before and after images of the ground. The satellite can also judge if the ground is being uplifted by measuring the distance between the satellite and the ground.

Question 23

Monitoring mass movements and failure landslides

Answer 23

Monitoring mass movements and failures landslides, rock falls, pyroclastic flows, and mud flows (lahars) are example of mass failures of volcanic material before, during, and after eruptions.

These can be monitored to show evidence of past activity and to suggest if upwelling magma is deforming the land above.

Question 24

What can be established using previous eruption evidence?

Answer 24

Safe zones

Question 25

What is the advantage of modern technology?

Answer 25

That sensors can be placed and observations and recordings can be made at a safe distance and immediate changes can be noticed.

This can increase the speed of evacuations and save lives

Question 26

Protection

Answer 26

As erathquakes can’t be prevented then reducing any damage is the only way forward for earthquakes prone areas.

Question 27

What are the 3 areas of protection in Japan focussed on?

Answer 27

• making buildings more earthquake resistant
• raising public awareness about prevention through education
• improving earthquake protection

Question 28

How can buildings be protected?

Answer 28

• in densely populated areas there will be a variety of building strategies used
• Single storey buildings are less likely to collapse
• reduce population density and so fewer casualties
• some have shock absorbers with rubber bearings
• some have pendulum bearings to allow a building to sway
• some have deep foundations
• some buildings are stepped-wide base and a narrow top for stabilty

see diagram in your binder

Question 29

What can be done for public awareness/education

Answer 29

The public in Japan are fully educated in how to react an earthquake, these “drills” are practiced in schools, workplaces, public buildings etc.

This reduces casualties significantly.

Question 30

What are people encouraged to have in their house in Japan

Answer 30

An emergency kit which includes a first aid kit with emergency water, food a blanket, whistles, torch, etc. This is done in case people are trapped in buildings and have to wait to be rescued.