Comparison of 2 volcanoes What power do geophysical hazards have to affect people in different local contexts? Two volcanic hazard events in contrasting plate boundary locations

Hazard profiles How does the nature of geophysical hazards vary between places and events?

Montserrat

Location of Montserrat Use the map provide write a detailed description of the location of Montserrat and the volcano.

Cause of the eruption… Destructive plate boundary (convergent) North American Plate is being forced (subducted) under the Caribbean plate Convection currents pull the plate into the mantle causing the rock to melt. The molten rock is lighter than the surrounding rock which causes it to rise through the cracks towards the earths surface

Cause of the eruption The volcanic eruption was so deadly because the volcano produced sticky andesitic lava (thick lava). The lava is so thick it created a dome on the side of the Chances Peak volcano. As the dome collapsed a huge ash cloud was formed. Also the dome collapse caused hot rocks, gases and ash- a pyroclastic flow.

Monitoring of the volcano from the MVO

In August of 1997, a series of pyroclastic flows and lahars (mudflows) destroyed the capital city of Plymouth. Photograph by Adam Goss http://people.cornell.edu/pages/arg32/watson/montserrat.html and used with permission

Exclusion zone in Montserrat- pre-event strategy Nearly 8,000 people out of a total population of 12,000 left the island for nearby Antigua, some went to the USA and Britain. It was predominantly the skilled middle classes, young people and women with small children who left in 1997

Pre- event management strategies for Volcanoes

Those who stayed on Montserrat Residents evacuated to the north of the island Temporary housing provided (low quality) 50 sharing a toilet which was only cleaned once every few weeks Risk of contaminated water and spread of disease such as cholera All public services had to be moved from South of Island to North A lot of elderly dependents left behind

Long-term management of hazards Rescue: Saving people so they can survive despite only having minimum life necessities Rehabilitation: Restoring the functions of public services, a process that takes one or two years Re-building: rebuilding the public system, economic system, governance and public structures, predicted to take 2 to 5 years.

Long term impacts http://america.aljazeera.com/articles/201 6/2/14/two-decades-after-volcano- eruption-many.html There are some 500 people still on a list for government housing assistance on the island, a British Overseas Territory some 30 miles from Antigua. Many live in the meant-to-be-temporary homes — a step up from the crowded, unsanitary emergency shelters in the island’s schools and churches, but built out of light wood paneling not meant to withstand the elements for more than a few years.

Long term impacts- positive https://www.theguardian.com/world/2016/jan/28/ montserrat-volcano-british-territory-geothermal- energy-tourism-sand-mining Geothermal energy, sand mining and tourism are the future.

Event profile Montserrat A phreatic eruption,  occurs when magma heats ground or surface water. The extreme temperature of the magma causes near-instantaneous evaporation to steam, resulting in an explosion of steam, water, ash, rock, and volcanic bombs. Event profile Montserrat Start date: Began on 18th July 1995 Magnitude: VEI 4 Speed of onset: Gradual – the volcano started giving off gas, ash and steam in 1995. The first phreatic explosion occurred on 21 August 1995, and such activity lasted for 18 weeks until it caused an andesitic lava dome formation. This period lasted for another 60 weeks, after which there were major dome collapses and two periods of explosive volcanic eruptions and pyroclastic flows. In 1997 a major eruption devastated the southern part of the island and buried the capital, Plymouth. Duration: 4 years – 1995-1999 . However, the volcano is still under-going an active period and so it is still not safe to resettle the south of the island. Area affected: 2/3 of the Island of Montserrat has had to be permanently evacuated. Frequency: The volcano had been dormant for 400 years prior to the eruption that began in 1995. There was a dome collapse in 2006 that resulted in a tsunami. The volcano has been relatively quiet since 2006. Predictability: The eruption was predicted as a result of the monitoring of the Montserrat Volcano Observatory. The capital city of Plymouth was evacuated after the first smaller eruptions of gas, ash and steam. Primary hazards: Pyroclastic flows, volcanic bombs, ash fall Secondary hazards: Lahars, tsunami (1 metre) Proximity to hazard: Rural areas, such as small villages that were farming communities and the capital city of the island (population 4000). Deaths: 19 (inside the exclusion zone)

Eyjafjallajökull, 2010

Location The mountain lays within the country’s East Volcanic Zone. Its name is derived from an Icelandic phrase meaning “the island’s mountain glacier,” and the volcano itself lies beneath Eyjafjallajökull (Eyjafjalla Glacier). Its highest point rises to 5,466 feet (1,666 metres) above sea level.

Cause of the eruption (process) Convection currents are driving apart the North American plate (moving West) and the Eurasian Plate (moving East) along a constructive or divergent plate boundary.   This is creating the Mid Atlantic Ridge, along which the age of the rocks either side of the ridge have been used as evidence of Plate Tectonics theory.   The plates are moving apart at a rate of 1cm to 5 cm per year. This has created a chain of volcanoes along the SE Rift zone of Iceland, which runs from NE to SW across Iceland, even passing underneath some of the countries Ice caps.  Divergent plate boundary Composite Volcano

Hazard Profile (magnitude, speed of onset, duration, frequency and spatial extent)   Start date: March 20, 2010

Watch: Make notes on: -What were the risks to the local population -How the volcano is managed

Effects of the eruption within Iceland Areas were flooded because of the glacier melt water which lay above the volcano. Agricultural land was damaged, and farms were hit by heavy ash fall. The ash fall poisoned animals in nearby farms. Some roads were destroyed. People were asked to stay indoors because of the ash in the air.

Effects of the eruption within Europe Travel was severely disrupted as many flights were cancelled between 14 and 21 April 2010 The eruption produced 0.3 cubic kilometres of ash, which resulted in the disruption of 95,000 flights across Europe and economic losses of 5 billion euros.  Businesses lost trade. Air operators lost millions of pounds each day. Perishable foods were wasted as they could not be transported. People were not able to get to work because they were stranded. The timing of the disruption was during the Easter holidays when levels of tourism are high.

Link to HL: impact of volcano on manufacturing

Link to HL- Impact on flower industry in Kenya

Measuring the explosiveness of volcanoes (volcano explosivity index)