Volcanic eruptions case studies

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The Mount St. Helens eruption 1980

General info:

May 18th 1980, 8:32 am

Washington State, Cascade Mountain Range

5.1 richter earthquake triggered the eruption

Biggest landslide recorded as North side of the volcano collapsed

Juan de Fuca plate and North American Plate, destructive

Environmental impacts

Lahars covered a huge area, created by melting ice

Ash and lahars blocked rivers killing all fish and water life

Spirit Lake was filled with mud which killed 12 million salmon

Sediment carried in the Columbia river

400m blown off the top of the mountain

One mile 500m deep horse-shoe shaped crater was created

Every plant and animal within 25km North was killed, 7,000 animals die

Every tree within 30km was flattened

Economic Impacts

Ash destroyed crops and roads

Nuée ardente destroyed forests and logging camps, timber industry was destroyed costing $300 million

250 homes, 47 bridges, 15 miles of railways and 185 miles of highway destroyed

Ash damage to farmers crops and machinery totalled £100 million

15cm of ash fell, traffic chaos and flights cancelled

Tourists no longer visited the area

Removing ash cost over $1 million in the town of Yakima

Social Impacts

63 people killed by poisonous gas, 90% outside of evacuation zones

Telephone and electricity cut

Removing ash took 10 weeks

Immediate response

National guard helicopter saved 130 people

Overall 198 people saved

National guard provided clean water, food and medicine

The federal government provided gas masks

Ash was cleared from towns such as Yakima in 3 days

Long term responses

10 million trees were replanted

1 million tonnes of ash was removed from roads

The Toulte, Columbia and Coulitz rivers were dredged

Warning plans were improved

Bridges were rebuilt with wider spans

Predication and management

There were warnings

From March onwards there had been minor earthquakes

Small ash and steam eruptions during 2 month prior to the eruption

Bulge on the North side of the volcano showed magma was moving up into the chamber

Tilt meters used to monitor changing size

Used past eruptions to identify danger zones

Emergency helicopters and aeroplanes were on hand

Landscape had changed so much so maps were no longer accurate

Compensation given to farmers worth $70 million

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Eyjafjoll (Icelandic) volcanic eruption 2010

General info:

South of the Arctic Circle

North American Plate (West) and Eurasian Plate (East)

Divergent plate boundary

Mid-Atlantic Ridge runs through

Eruption:

20th March begun eruption, main eruption occurred 19th April

Fissure eruption, lava flow more dominant of the West and East side

Ash plume rose to 11,000m

Ash was fine grained, 24% is under 10um, the same as aerosol

Ash distributed by high velocity jet streams

150km thick ice cap melted which caused flooding to Iceland

700 people evacuated

Destroyed main Route 1 road

Roads bulldozed to allow the flash flood water to reach the sea

Fine ash silted rivers, blockages a year on

Government paid to dredge rivers or allow them to flood to c

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Mount Pinatubo eruption 1991 Philippians

General info:

•Island of Luzon,

South East Asia

•Eurasian and Philippine Plate

•Luzon volcanic arch

About the eruption:

•April 2nd 1991, hypothermal explosion, this caused steam

and small ash clouds reaching up to 800m and rumbling

•Temporary seismic station at Sitto Yamut placed three days

after steam, recorded 223 high frequency volcanic earthquakes during operation

of the first 24 hours

•April 6th-June 6th, 26 to 178 HFVQ's a day

•Earthquakes caused by fracturing rocks and moving fault

structures

•June 7th, daily incidence of earthquakes 1,500-2,000, and

low frequency earthquakes begun to occur indicating magma rising to the surface

•Earthquakes became shallower

•June 9th, harmonic tremors recorded indicating intensified

seismic activities

•7:30am June 3rd first ash ejection which lasted for 30

minutes

•June 4th, more ash ejections at short intervals

•9th June, eruption occurred at 6am

•Pyroclastic flows reached 4-5km away from the volcano

•Philvolcs issued Level 5 alert at 3:15pm

•Eruption lasted for a week

•5 billion cubic meters of ash and debris ejected

Environmental

•Water contaminated

•Volcanic ash blown in all directions over hundreds of miles, reaching Russia and North America

•Lahars causes severe river bank erosion

•Global cooling caused by the ash in the atmosphere of 0.5 degrees

Economic

•650,000 workers lost jobs

•$700 million damages

•Houses and bridges destroyed needed replacing and Manila airport had to close

•Farmland destroyed by falling ash and pumice making it unusable for years

•1991 harvest was destroyed; this caused jobs to be lost

•Provinces of Zambales, Pampanga and Tarlac worst hit, 86,000 hectare of agricultural lands damaged

•Ninoy Aquino airport closed for four days

•Heavy rainfall from Typhoon Yunga causes buildings to collapse

•Road links were destroyed

Social

•847 killed, 300 killed by collapsing roofs, 100 killed from lahars, the rest killed from disease

•58,000 people had to be evacuated from a 30km radius of the volcano to shanty towns in Manila

•1.2 million people lost their homes

•No electricity and telephone

•Metro Manila, dust blanketed the metropolises suspending classes for a few days

•Americans forced to evacuate Clark Air Base, ash rendered runways useless

Response- Prediction, before eruption (Seismology prediction management case study)

•No monitoring until the 3rd April, but seismometers put in place

•75,000 people evacuated due to accurate predictions

•United states geological service helped predict the disaster

•Warning signs such as gas and steam looked for

•Evacuation camps prepared for refugees

Response-Prevention, during eruption

•Alert systems put in place to warn of eruption

•USA air force helicopters helped in evacuation

Response- After eruption

• By December 1991, 61 municipalities and two cities declared as calamity areas

•Government shelters

•Placed strategies for long term aid and disease control in

evacuations prepared for

•Long term and short term aid organised especially from the

Red Cross and the United States

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Mt Sakurajima mangement

Kagoshima government has put several measures in place to manage the risks of the volcano

Japan sets and adopts the international standard of Volcanic Hazard mangement

Law and enforcement

Laws enacted to allow all phases of prevention, mitigation, preparedness, emergency response, recovery and rehabilitation to be enacted.

Disaster Countermeasures Basic Act (1961)

Erosion Control Act (1897)

Disaster relief Act (1947)

Building Standard Law (1950)

Landslide Prevention Act (1958)

River Act (1964)

Act on Special Measures for Large-Scale Earthquakes 1978)

Public Information

Television and radio channels, newspapers and public education campaigns

Evacuation routes

Do's and don'ts

Information helpline

Assures the public that they are in control of the situation

Government holds widely publicised annual disaster properness drills

Prior to the 5th February eruption, 16th January excursus was held

Preparing

Japanese Meteorological Agency and Kyoto University Sakurajima monitors the volcanoes activity

Information is widely available to the public

Managing the effects

Yet to cause damage to Kagoshima city due to the preventative measures in place, but preparations are in place just in case

The Basic Disaster Management Plan prepared by the Central Disaster Management Council in accordance with the Disaster Countermeasures Basic Act

Duties assigned to the Government, public corporation and local government

Describes the sequence of disaster counter measures

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Mount Etna eruptions

Most active volcano in Europe

25% of Sicily's population live on the slopes of Mt Etna

Decade volcano

Since 2001 Mt Etna has had an eruption every year

Destructive plate boundary, seduction of African plate beneath the Eurasian plate

About the eruptions

Wide range of eruptions, minor to major

Strato volcano

Basaltic lava, low viscosity so can travel large distances

Fissures open up in the volcano releasing lava from a variety of locations

Seismic activity can pose a threat

Eruptive columns of ash, significant problems to settlements and agriculture

Risk of flank collapse which can cause a landslide

Risk of phreatic eruptions

Impacts

77 confirmed deaths, recently there have been few fatalities

2002 eruption destroyed the tourist station at Piana Provenzana and Rifugio Sapienza

29th July 2002, Catania airport closed for 4 days causing winter tourist industry to be affected

Ash reached as far as Libya

magma thrown over 100m into the air

Linguaglossa was evacuated , over 100 people had to leave there homes

Skiining areas wee damaged by lava flow, a restruant was destroyed and ski lifts

Hundreds of hectres of forest was destroyed

300 family businesses losrt earnings

Responses

Tried to divert lava flow when it threatened the scientific monitoring area

Taramac cracked to try and create a channel to direct lava flow away from Linguaglossa

A medical clinic ship was sent to Catina

Tax breaks were given to the people affected

£5.6 million was given in immediate inacial assistance

Management

Catina section of the institiuto Nazionale di Geofisica e Vulcanoliga has monitored the volcaneo for 20 years with permantant remote sensors

Data is continuously recorded

Geochemical monitoring programmes test gas/fluid emmisions to help predict new eruptions