Volcanic casestudies

When was Mt. Ontake’s eruption

27th September 2014

Where is Ontake

It is a volcano on the island of Honshu, 200km SW of Tokyo (rural area)

AO2 point on location

Being in a rural area, any effects from the eruption were restricted to the surrounding area - unlike the other eruptions (eg EJF - had international impacts). 

What makes Ontake a point of interest

Standing at 3067m, it is the second highest mountain in Japan - tourism

what time of day did ontake erupt

11:52am

What is Japan’s GDP

38,400

What day of the week was the eruption

Saturday - sunny, lots of civilians walking in the area.

How did the time of day influence the eruptions impacts

Hikers would most likely be at the top of the mountain by then - lunch break. They couldnt get away as much closer to where the eruption was. 

What type of eruption was mt. ontake

Phreatic

What is a phreatic eruption

A steam driven eruption, occuring when water held underground is heated. There is no lava or pyroclastic flow

What was occuring under the surface of mt. Ontake

Water that was held in aquifers seeps into the volcano underground in a geothermal system. Magma boils this water, and it forces the steam out of the volcano

What was Ontake’s VEI

3

What type of volcano is mount ontake

A stratovolcano - however, the eruption didnt behave in a typical way. 

How much ash covered the mountain

40 to 50cm

Draw a diagram of the plate boundaries at mount. Ontake

… (Destructive/convergent boundary of Eurasian and Pacific plates)

For how far did the ash go down the mountain

3km

Perception of place - how did people say the ash felt like on Ontake

“it sounded like thunder” “rocks fell like hailstones”

What exacerbated the impacts onto the rescue mission (e.g. people related thing)

All hikers were meant to register at the base before embarking on the trek - hazard protection

How many people actually registered with tourism officials at Ontake

10 to 20%

Total death count of Mt. Ontake

57

How many people were injured from Ontake

40

How many people were classed as missing

6

What is tephra

The collective term for all pyroclastic material ejected from a volcano

What speeds was the tephra flying at from the volcano

300km/hr —> led to more injuries

What did over half of those dead have on their phones

Photos of the eruption & many holding them when found.

Where were majority of those dead found in Ontake

At the summit resting/eating lunch

What agegroup were majority of the victims

30 to 59

How big was the rescue mission for Ontake

1100 firefighters and police

Why was the rescue mission abandoned on the 29th 

High levels of hydrogen sulphide in the air

How many were in Ontake’s resumed search party in July 2015

220

Why was the resumed search party so delayed

Natural hazards surrounding the area - the volcanoes continued activity; effects following local typhoon.

Political impact - why did the country begin to argue / loose faith in the JP gov,

2 seismographs were faulty ontop of Ontake, but left unfixed. People felt this was the cause of the eruption

Why would any attempts to mitigate against teh event be useless

Its status as a phreatic eruption made it impossible to be tracked on a seismograph. Temperatures barely hit 100 degrees C & seismographs look for 2000+

How much money in lawsuits was brought by the families of the dead against the JP gov.

£1 million

When was Mt. Merapi’s eruption

26th October 2010

Where is Mt. Merapi

Java, Indonesia

What is the population of Java

136 million (most populous island in the world)

What is Indonesia’s GDP per capita (as of 2010)

$3000 USD

What type of plate boundary does mt. merapi lie on

A destructive plate boundary

What two plates collided at Mt. Merapi

Indo-australian and Sunda (Eurasian)

Draw a diagram of the plate boundary collision occuring at Merapi

What is Mt. Merapi

The most active volcano in Indonesia (and also a stratovolcano)

When did Merapi previously erupt

• 2006

• 1994 - killed 27

Why are Merapi’s previous eruptions significant (AO2)

Perception of place/eruption - many would remember the prior eruptions; their dangers/ impact. Maybe more equipped to prepare?

Why is Merapi’s location impactful

Towering over central Java and Yogyakarta - densely populated, impacts lots of people.

How far is Merapi from Yogyakarta

28km

What is the population density of Yogyakarta

12,000 /km2

Why was an evacuation order issued pre the eruption (merapi)

Following 500+ earthquakes at the volcanos summit on the 23rd/24th October.

How many people were evacuated & within what radius (merapi)

20,000 evacuees in a 20km radius.

What was the VEI of the eruption (Merapi)

4

What time did Mt. Merapi erupt

5pm

How many died from Merapi’s eruption

350

What type of eruption was Merapi

Explosive. Powerful and pyroclastic

What did majority of the fatalities from Merapi have in common

They were most commonly people who had refused to evacuate, or returned to their homes between eruptions

How were fatalities caused (Merapi)

Fires, burns, respiratory failure and blast injuries

How long did Mt. Merapi erupt for

Over a month - continuing throughout November.

How many were displaced by Merapi

350,000

How far & high did volcanic ash fall (Merapi)

30km away, &6km upward. Impacted Java’s airspace.

How many were hospitalised with injuries (merapi)

487

Why were so many people impacted by Merapi

Being an EDC, many rely on farming (subsistence). Volcano provides fertile soils & cheap living 

How many hectares forest and farmland were destroyed by Merapi

870 hectares

How much GDP was lost by Merapi (in particular, money lost by farmland that was destroyed)

$3.6 million

Why was the time of year Merapi erupted significant

Nov. to April in Indonesia is rainy season → new hazard of lahars.

What is a lahar

A destructive volcanic mudflow formed when volcanic material mixes with water

How did lahars cause further impacts (merapi)

In the Magelang district, houses and farms were damaged up to 26km from the volcano. This was outside the evacuation zone. 3,000 were impacted. 

How did lahars impact the Amat river valley

21st January, lahars obliterated Rangjah and Kinaherjo villages. This killed 33 people and all cattle. Farming became impossible in this area → economic impact. 

How much did the Indonesian government allocate instantly to help the areas

$2.6 million USD - through the National Disaster Mitigation Agencey

What did the military do (merapi)

• Built makeshift hospitals and public kitchens in the safe zone

• Assisted by NGO’s - Indonesian Red Cross

How far from the eruption were schools closed (Merapi)

up to 120km away due to concerns over ashfall

What were the emergency shelters like for Merapi

In theory good, but very overcrowded and chaotic as people moved from shelters looking for family members.

What did the WHO do in collaboration with the Indonesian gov.

Distributing blankets & 6 tonnes of emergency energy biscuits. They also distributed 100,000 facemasks at the crisis centre, given out to shelters closest to the volcano. 

When was the Eyjafjallajökull eruption

14th April 2010

Where is Eyjafjallajökull

Southern Iceland, near to the coast.

What is Iceland’s population

300,000

What is Iceland’s GDP per capita

$43,000

What boundary is Iceland on

The mid-atlantic ridge - constructive plate boundary of the North American and Eurasian plates.

What was Eyjafjallajökull’s VEI

4

Draw a diagram of the Mid Atlantic ridge (Iceland’s constructive plate boundary)

Why was the Eyjafjallajökull a larger eruption than expected for a shield volcano

Volcano was 250m below icecap. As magma rose to the surface, lava that was being extruded passed through ice and melted it. This caused a jokulhaup.

How was Eyjafjallajökull’s explosivity increased

The mix of water an lava helped to eject ash high into the atmosphere. This led to arguabley the most sig. impacts of the eruption.

How high did eyj’s ash plume reach

10km

What is the polar jet stream

A fast flowing tunnel of wind. This was in a holding pattern of NW to SE, driving the ash over Europe

How did the volcano being under an icecap impact the ash

Melted ice cooled the volcanic material to a glassy ash with 58% silica content. The silica made the ash more explosive, allowing it to be pulverised and then made finer → travelling further. Rising magma melted the overlaying icecap and so water flowed into the crater - adding to explosivity. 

Why did the ash travel further (Iceland)

It was very fine, and so got caught in the polar jet stream

(Enviromnental) how were impacts mitigated locally

Tall grazing grass was thick - able to hold the ash close to the ground surface and stopped it from being blown around. Also helped soil to be more fertile

How many died in Eyjafjallajökull

0 deaths

How many were evacuated in Iceland

700, 3 times in the month.

How did the eruption impact infrastructure

The jokulhaup led to flooding; a main road was breached to allow water to flow safely to the sea. This was done to protect a large bridge

How did eyj impact economy

• Briefly paused tourism

• Flouride from the eruption was deposited on grazing land, causing haemorrhaging in cattle and sheep. 

How many flights were cancelled in Europe due to eyj

95,000

How many flights stopped in 24 hrs (heathrow only)

1000

What NGO helped eyj

European red cross - provided food for farming population, councselling

What are FABs & how will they prevent future impacts

They are Functional Airspace Blocks, replacing the 27 areas prev in place in the sky - if another eruption occured, the entire airspace wouldn’t be closed down.

How much money did Europe lose in GDP

$2.6 billion

what % of air passenger no’s fell

11.7%

How many brits were stranded abroad

40,000

Why was the time of year impactful

Right at the end of easter holidays - meant that students and teachers were stranded abroad. Pre =pandemic society, no digital infrastructure for online work. 

Positive impacts of eyj

• 2.8 million tonnes less of CO2 emitted

• Quality of life was said to improve (albeit momentarily)

• Ash helped farmers - fertile

• Channel tunnel and cross channel ferries did extra business

Eyj’s global economic impacts

Kenya & Thailand, both LIDC’s - flower cutting trade. Couldn’t be shipped, lost $3 million / day. Laid off workers, damaged them financially. 

Political impacts of Eyj

Obama couldnt attend the polish president’s state funeral

Prime mimister of Norway had to remotely run the country from NYC as unable to get a flight