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Last Updated: Sunday, 26 September, 2004, 12:16 GMT 13:16 UK
Montserrat volcano: Has it gone quiet?
By Aoife O'Mongáin

Soufrière Hills Volcano (AP)
A pyroclastic flow: One of the biggest dangers
The Soufrière Hills Volcano on the Island of Montserrat has been relatively quiet since the last major eruption in July 2003.

This may have lulled the local residents into a false sense of security.

An independent Scientific Advisory Committee (Sac) will meet on Montserrat this week to discuss the status of the volcano.

They will decide, from the scientific evidence presented to them, what the hazards are and if the levels of risk have reduced over the last six months.

This may lead to the Montserrat government opening up new parts of the exclusion zone.

The volcano started erupting in July 1995 and the eruption has essentially continued for the last nine years, causing major disruption to this small Caribbean island.

There was a sense in which the people didn't trust the scientific advice at the start of the eruptions
Joan Meade, methodist pastor
Out of a total population of 10,500 in 1995, up to 7,000 people have been evacuated from the island and the rest of the residents forced to live in the northern part of the territory.

The airport and the capital, Plymouth, have been destroyed.

Sticky problem

Methodist Pastor Joan Meade describes what is left of one of her parishes.

"My largest congregation was in Bethal," she told the BBC's Science In Action programme. "There are no dwelling houses or schools in the area anymore, so it wouldn't be a question of people returning home."

Hazards on Montserrat are caused by the creation of a lava dome.

"The lava is not fluid, it doesn't flow out easily," explains Professor Geoff Wadge, chair of the Sac. "It is very sticky, viscous and it tends to stay where it is as it comes out of the ground.

Map showing island exclusion zone (BBC)
"A large pile, 300m high and 1km across, forms on top of the volcanic vent.

"Occasionally, the process is disrupted by explosions which send up large columns of ash and rock fragments which rain down. These ash clouds reach as high as 15km above the volcano."

The other hazard is that the dome is unstable and can collapse, often without much warning. This produces extremely dangerous pyroclastic flows - very rapid flowing avalanches of hot rocks, ash and gas which can move down the mountain at speeds of 100-150km/h.

"It is impossible to outrun them; they are totally deadly to anything in its path," says Professor Wadge.

Disappearing top

It was difficult to persuade some people to leave their homes, and residents looked to Joan Meade for independent advice. Many were worried the scientists had an ulterior motive.

"There was a sense in which the people didn't trust the scientific advice at the start of the eruptions," she says.

"That changed with the fatal eruptions in June 1997; people took the scientists more seriously... they saw that it could kill people."

It is hard to comprehend the scale of the volcano and what it looks like before and after one of these fatal collapses.

One day the mountain's top can be in the clouds; the next day the top two-thirds of the volcano are gone, collapsed into the sea. It is a dramatic change to the landscape.

July 2003 was the last collapse of this sort and luckily the scientists correctly predicted where the debris from this collapse would go and the people were evacuated.

Since then, the dome has stopped growing, leading people to ask if the eruption has finished.

The Plymouth issue

The risk assessment meeting will address this. Professor Wadge says the role of the committee is to review, every 6 months, the status of the volcano and the hazards and risks that are posed to the people of Montserrat.

"We act in conjunction with the Montserrat Volcano Observatory, managed by the British Geological Survey," he adds. "They run the day-to-day monitoring of the instruments that provide the data to understand what is going on."

The advice of the scientists is then passed on to the government of Montserrat.

Soufrière Hills Volcano (AP)
Many homes and government buildings are buried under ash
But has the eruption finished now or not? If the eruption is not finished, the scientists need to assess the likely hazards the local population will face over the next year.

They do this by running computer programs to simulate the hazards related to explosive eruptions which can shower down large particles that can maim or kill people.

They also try to simulate the path any pyroclastic flows are likely to take. "By doing this, we can build up a quantitative measure of the likely distribution of these hazards," Professor Wadge explains.

When asked if it was likely Plymouth would be opened up Professor Wadge says this decision will rest with the government.

"The difficulties faced by the government - this is not the area of the scientists - is that most of the utilities... are inoperative and it would take a huge amount of money to get them up and running."

Rather than waiting for the volcano to stop, the government is concentrating its efforts on rebuilding the island.

A new airport is already underway and there are plans to relocate the capital.

"We are looking at Little Bay as our new town and that is in the northwest of the Island," says Janice Panton, head of the Montserrat Government in the UK.

"It's a nice bay, a wonderful site and we are all looking forward to it very much."

Soufrière Hills Volcano before and after blowing its top (MVO/BGS/Government of Montserrat)
Soufrière Hills Volcano before and after blowing its top (Image courtesy of MVO/BGS/Government of Montserrat)

Science In Action's Aoife O'Mongáin
"The question is: is it safe?"

Regions and territories: Montserrat
18 Sep 04  |  Country profiles
Ash rains down on Montserrat
13 Jul 03  |  Americas
Volcano teaches deadly lessons
19 Feb 99  |  Science/Nature

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