33 Marker: Volcano Hazards responses over time

‘Over time the ability to manage hazards from volcanic activity increases.’ Examine the extent to which this statement is true. [33]

Three main arguments?

1. Impacts of hazards associated with effusive & explosive eruptions.

2. Modifying strategies

3. Mitigating volcanic activity

Intro (1st part)

• Number of natural disasters has increased through time. However, the increase in frequencies of volcanic hazard events is less pronounced.

• Although there’s been an increase in measuring & reporting volcanic activity which has become more reliable over the past century, human activities play no part in causing volcanic eruptions. But, human factors have a significant bearing on the impacts of volcanic hazard events.

Intro (2nd part)

• Past 50 years: there has been an increase in the number of disasters due to VEs.

• The British Geological Survey suggests that there are around 1500 active volcanoes on earth, with 50-70 eruptions per year.

• Fatality numbers have been affected and economic cost have years that stand out as being exceptionally disastrous e.g. Mount St Helens in 1980.

• However, it can be argued that the majority of years most geophysical events, including volcanic activity, has had limited impacts e.g. the volcanic eruptions seen in Hawaii.

Hazards associated with VEs: Lava Flows

• Impacts dependent on type of lava.

• Basaltic lava = free-flowing and can run for considerable distances.

• Acidic lavas e.g. rhyolite, = thick & pasty and do not flow easily.

• Everything in the path of lava will be either burned, bulldozed or buried.

• Although they destroy infrastructure, property & crops, lava flows rarely causes injuries or fatalities.

Examples of lava flows on Hawaii?

• Hawaiian Islands experience effusive volcanic activity, where eruptions are categorised by the outpouring of lava flows.

• Lava on Hawaii can either be Pahoehoe (smooth, rope-like surfaces) or A’a (jagged, rough or clinkery).

• However, since these lava flows are frequent and flow freely, they are not considered a major hazard, although they’re locally destructive.

Other examples of lava flows?

E.g. Kilauea eruption (1983-2001) destroyed 13km of highway, approx. 180 buildings including almost the entire destruction of the village Kalapana.

E.g. Hawaii (July 2015), a lava flow extended for 20km before stopping, and in August, a flow was reported to have covered about 800m in a day.

Hazards associated with VEs: Pyroclastic flows

• Combination of very hot gases over 500 degrees C, ash and rock fragments that travel at high speeds of around 100km/h.

• They follow the contours of the ground & destroy everything in their path.

• The inhalation of such hot and poisonous has & ash causes almost instant death.

• E.g. Mount Vesuvius – Pompeii was overwhelmed by pyroclastic flow in AD79.

Example of pyroclastic flows?

• Mount Ontake, Japan (2014): erupted violently without warning.

• Eruption killed 63 people & large areas surrounding volcano were affected by ash fall, pyroclastic flows, volcanic bombs & lahars.

• 0.5m of ash covered the local area, which was mostly collected on roofs that caused them to collapse under the weight.

• 40 people were majorly injured and unable to work.

How were the impacts of Mount Ontake worsened by the lack of preparedness?

• Although the military was ordered by the Japanese prime minister to assist with emergency rescue operations, they found that 2 seismometers were faulty but were left unfixed.

• Therefore, a lot of the country lost faith/confidence in the government – will not help with future volcanic eruptions.

• £1 million lawsuits were brought by families of the dead against the government.

Hazards associated with VEs: Tephra

• Material ejected from a volcano into the air – ranging in size from very fine ash to large volcanic bombs that are larger than 6cm across.

• Larger pieces of tephra that are greater than 64mm, are called blocks and bombs that are shot ballistically from the volcano.

• Smaller ejecta, such as lapilli is between 2-16mm, and ash which is under 2mm falls out further.

• Most particles greater than a mm will fall out within 30 mins of the time they’re erupted.

Example of tephra: Mount St Helens

• Mount St Helens (1980) – secondary thickening occurred & ash deposits were thicker in one certain area compared to surrounding areas.

• This results when ash particles & water form clumps, producing larger particles with higher terminal velocities, so fall out of the ash cloud.

• Around 10mm of ash covered the town of Yakima, approx. 80 miles east of the volcano.

Example of tephra: Indonesia

• Merapi volcano (2010) – lava bombs were thrown 4km from summit in all directions.

• Eruption also happened at the start of the rainy season which triggered lahars fed by ash from the eruption & from earlier eruptions.

• Ash fall forced closure of Yogyakarta airport for over a fortnight.

• 367 killed while approx. 410,000 in the vicinity of the volcano became refugees.

How were the impacts of Merapi worsened by the lack of preparedness?

• Eruption tested the govs ability to respond effectively to natural disasters & manage crisis situations.

• Highlighted the need for improved disaster preparedness, response mechanisms & coordination among government agencies.

• Criticisms of slow or inadequate gov action could lead to public dissatisfaction & affect governments credibility & popularity,

• Long term effects – social unrest & discontent among affected populations.

However, what makes Indonesia complex?

• Indonesia’s tectonic setting is complex, as there is widespread subduction along the entire 3000km length of the Indonesia archipelago.

• Much of Indonesia is an island arc formed by subduction of the Indo-Australian plate beneath the Eurasian plate.

• Meanwhile, to the east of the chain of islands, the continental shelf of northern Australia is in collusion with the Eurasian plate.

• These plate movements produce very high levels of volcanic activity, where over 75% of Indonesia’s population inhabitants live within 100km of a volcano that has erupted in the past 10,000 years.

How can it be argued that many eruptions are managed better as many are less destructive?

• It can be argued that these hazards have been managed better over time since in some cases, the type of volcanic eruptions have been less destructive.

• E.g. explosive eruptions on Hawaii are rare, however Kilauea has experienced two main recorded periods of explosive activity in 1790 and 1924.

• This was assumed to have resulted from expanding steam generated from heated water on or near the ground as it mixed with magma ad hot rocks.

• From Kilauea’s 1790 eruption, fields of volcanic debris have formed, some are 35 feet deep in some places.

Argument 2: 3 Modifying Strategies?

1. Modifying the event

2. Modifying people’s vulnerability

3. Modifying loss

How can the volcanic event be modified?

• Although it is not possible for the vast majority for VE.

• However, the following have been tried with some success.

  • Lava-diversion channels.

  • Spraying lava to cool & solidify.

  • Slowing lava by dropping concrete blocks.

Recent example of volcanic event being modified?

• E.g. Eruption in Reykjanes Peninsula (Dec 2023)

• Lava reached eastern defences around the evacuated town of Grindavik.

• Many protective embankments were built around lava beds & concerns about fibre optic cables on the road could be damaged – disrupting phone and internet services.

How can people’s vulnerability be modified?

• Education: Recognising signs of possible eruption & what to do when an eruption occurs.

  • E.g. evacuation routes, drills to practice what to do when eruption occurs.

• Prediction & warning: increasing use of technology to monitor particularly active locations e.g. individual volcanoes.

• Land-use zoning: avoid building in locations identified by hazard mapping i.e. vulnerable to hazards from volcanic eruptions.

How can people’s loss be modified?

• Emergency aid: medical supplies, water, food packs, tents etc.

• Disaster-response teams & equipment: e.g. helicopters & heavy lifting machinery.

• Search & rescue teams.

• Insurance for buildings & businesses.

• Resources for rebuilding public services e.g. schools & hospitals, help for individuals to rebuild homes & businesses.

  • E.g. Indonesia has initiated temporary shelters in safe zones that are available in case of evacuation & sometimes these are upgraded into permanent residential areas.

What are the changes over time in Indonesia in terms of modifying people’s vulnerability & loss?

• Since Indonesia is an EDC, resources that it can deploy once eruption is underway are limited.

• Centre for Volcanology & Geological Hazard Mitigation (CVGHM) established in 1920 – permanent observations on several active volcanoes.

• 1st seismograph was set up on Mount Merapi in 1924 – but capability of technology at the time was limited.

• Managing volcanoes has been low priority in last century – end of WW2 Indonesia become independent as it was a Dutch colony, this accompanied political tension & violence.

• CVGHM has upgraded the monitoring instruments & widened their geographical coverage.

• Over 60 volcanoes are monitored.

• Sophisticated equipment e.g. measures gas emissions, inflations such as magma rises.

Recent Merapi eruption improvements?

• Argued responses have improved e.g. Mount Merapi erupted again in December 2023, killed 11 hikers.

• However, most hikers were safely evacuated & medical services available to help injured.

Argument 3: Mitigating VA using Technology.

Core Methods & Radar Interferogram

• Core methods: seismic – movement of magma that generates unique seismic patterns.

• Ground deformation – amount of ground movement.

• Radar interferogram – shows pattern of ground uplift cantered about 3 miles west of South Sister Volcano in central Oregon.

• Each band of colour represents ground movement in the direction of the radar satellite.

Seismic Monitoring?

• Seismic monitoring – ideally, 6 or more local seismic stations (within 15km).

• Several regional stations over 15km away. All capable of detecting very weak volcanic quakes beneath the volcano.

• Over 25 successful seismic monitoring successful forecasts: e.g. Montserrat (1995-7), Pinatubo (1991), Mayon (1993) etc.

Volcano seismicity?

• Very different to earthquakes.

• 5 main types of seismic event: High frequency, low frequency, tremor, explosion, surface (rock falls, lahars).

• Pre-eruption quakes are typically swarms, increase in number & occur close to the eruption location.

Volcano deformation: Principles & Methods?

• Low cost & assessable for wider range of countries.

• Either tilt measurement, lateral displacements, vertical displacements or space based.

• However, there are problems e.g. tilt measurement – site-specific & no measure of absolute altitude change or horizontal movements.

Predicting Hazards: Hazard Zonation

• Hazard zonation: predicts future hazards on basis of past activity.

• Can be constructed for single or all hazards.

• Dependent on representing preservation.

• Require detailed geological mapping, dating & correlation.

• Aided by computer simulations.

• Boundaries must be regarded as approx. & conservative.

• Helps to know where to place homes/services/agriculture etc.

Example of hazard zonation?

Zonation map of Mount St Helens 1980 eruption deposits – informs future planning for places.

Pros of predicting eruptions?

• Can inform of risk awareness & education – critical in reducing impact of volcanic eruptions.

• Progressive programme: raising awareness of threat, education about nature of threat, training in preparedness & crisis response.

• E.g. Taiwan – small number of events in recent eruption due to preparedness & education.

Geoengineering volcanoes debate: Lake Nyos, Cameroon example?

• 1986: cloud of CO2 emerged from a volcanic lake (Lake Nyos) in Cameroon – over 1,700 people and 3,000 livestock were suffocated.

• Prevented this from happening 3 years later using garden hose, then later bigger pipes. Since, CO2 gas levels have been successfully controlled.

Geoengineering volcanoes debate: Reykjanes Peninsula

Shows geoengineering can save lives e.g. recent volcanic eruption in Reykjanes Peninsula, authorities have re-directed lava flows.

Geoengineering volcanoes debate: Mt Kelud, Indonesia example?

• 1919: lahar killed over 5,000 people at Mt Kelud in Indonesia – engineers drilled tunnels through the crater to drain the lake.

• When it erupted in 1951, the lake’s volume has reduced by 90% so the lahars were less destructive.

Risks & Ethics with geoengineering volcanoes?

• Risks & ethical quandaries e.g. trolley-problem quandaries like whether to send the lava to destroy one person’s home to save 5 others.

• Legal ramifications could arise – following Italian earthquake in L’Aquila, 6 geologists were convicted of manslaughter, after failing to predict the magnitude of a quake, authorities blamed them for giving false reassurance.

However, what are the global-scale ethics with this?

• Global scale ethics – some volcanoes have religious importance, could affect economies and climatology.

• E.g. Eyjafjallajokull in Iceland erupted in 2010 – grounded thousands of planes across Europe and costs ran into billions.