MANAGEMENT OF SOUFRIERE HILLS ERUPTION
MANAGEMENT OF SOUFRIERE HILLS ERUPTION
- Created by: katie silvester
- Created on: 09-06-12 18:19
CASE STUDY: Soufriere Hills eruption, Montserrat,
After lying dormant for centuries, the volcano began to erupt:
- early activity included ash emissions, steam explosions & numerous eq's - the steam & ash reaching heights of over 2,500m
- volcano entered quieter period for a while
- March 1996 - again produced a huge ash cloud, aswell as dome growth & small pyroclastic flows
- early 1997 - continued dome growth with small explosions & ballistic projectiles
- climax occured on 25 June - large explosions within the volcano resulted in extensive pyroclastic flows (holding 4-5million m cubed of material)
- most of this material flowed down northern flank - damaging houses & causing death of the inhabitants
- only small amount of island was considered safe to live on
- the capital Plymouth, was eventually buried under 10m of ash & mud
- airport & docking facilities destroyed
- southern part of island rendered uninhabitable
Since 1997 - volcano has been relatively quiet with only minor activity
MANAGEMENT OF SOUFRIERE HILLS ERUPTION
During & after the eruption of the Soufriere Hills volcano, as Montserrat was still a dependent territory, the British had to provide/assist in the following:
- setting up of exclusion zones
- evacuation of 7,000 of the islands 11,000 inhabitants to neighbouring islands such as Antigua or resettlement in the UK - and then finacial help with resettlement
- resettlement of some of the population from the volcanic south to the 'safer' north of the island
- setting up temporary shelters in the north
- re-establishment of air & sea links with the island
- building of new permanent housing
- moving the capital from Plymouth to Salem
- providing farming areas for those resettled in the north
- setting up Monserrat Volcano Observatory to monitor the volcano's activity- today this is run under contract by the British Geological Society
UK government spent over £100 mill in assisting migration & restoring services, agriculture & employment on the island
By early 21st century - number of new homes had been built, although many inhabitants were still living in temporary accomodation
Other features of the islands redevelopment include:
- attempts to restore some of the tourism lost during the eruption
- the return of some of the refugee's from the UK & elsewhere
- construction of a new airport - cost £11 mill, opened in 2005
- development of port facilities at Little Bay
- construction of a new football pitch - mainly funded by FIFA
CASE STUDY: Mt Etna, Siciliy
Background:
- Mt Etna towers above the second largest city in Sicily - Catania
- has one of worlds longest documented records of eruptions- dating back to 1500 BC
- the stratovolcano (truncated by several small caldera's) was constructed over an older shield volcano
- most prominant feature is the Valle del Bove - a 5-10km horseshoe shaped caldera or depression open to the East
- this was created when the volcano experienced a catastrophic collapse during an eruption - generating enormous landslide
- Persistent explosive eruptions (sometimes with minor lava emissions) take place from one or more of the 3 prominent summit craters
- there are a number of vents on the side of the volcano from which lava emerges
- cinder cones are often constructed over the vents of lava flows on the lower flanks
- Lava flows have reached the sea over a broad area on the south-east flank of Mt Etna
- Although it can be destructive, volcano is not regarded as particularly dangerous
- thousands live on its slopes & in surrounding areas - working the fertile volcanic soils
Towards the end of 1991- lava began to pour from vents high on the eastern flank in the 'Valle del Bove' - advancing on the settlement of Zafferana
A series of protective measures were put in place:
- a large earth barrier was constructed across the end of the Val Calanna, at the southern end of the Valle del Bove - several 10's of metres high/more than 400m long
- Held back lava for several months (aim was to slow lava temporarily while other protective measures were put in place)
- during spring of 1992 - accumulation of lava began to spill over the barrier and travelled down into the valley towards Zafferana - Smaller barriers erected across valley were quickly overwhelmed by advancing lava
- decided to cut off the flow by blocking the primary feeder channel - first attempted by dropping concrete blocks from helicopters through the roof of the upper lava tube
- May 1992 - engineers blasted openings in the lava tube - attempted to encourage a new direction of flow away from Zafferana. This was successful
- eruption ended 10 months later in early 1993
Although propably the most successful attempt at changing the course of a volcanic eruption at the time - there remains doubts as to whether the flow would have even reached Zafferana anyway
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