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Soufriere Hills, Montserrat, West Indies



Pyroclastic flows from Montserrat dome collapses have flowed down the White River creating a new delta where they entered the sea. It is uncertain if this delta will survive or be eroded by seawaves
Soufriere Hills, a stratovolcano on the island of Montserrat, began erupting on July 18, 1995. This is the first recorded eruption of this volcano in historic time. The initial small phreatic eruption produced minor ash that spread around the island. Periods of intense seismic activity were associated with strong venting of steam and ash. A new vent formed southwest of Castle Peak, an old volcanic dome.

November 16, 1999
The activity at the Soufriere Hills Volcano was at a higher level between 5 November and 12 November. Distinct explosions occurred on the 8 and 9 of November, followed by two hours of tremor. Both explosions created steamy ash clouds which rose ~20,000 to 25,000 ft. above the volcano. A light ash fell on Monserrat. Small pumice clasts were found near the volcano. On 11 November, a small dome-collapse pyroclastic flow occurred in the upper parts of the Tar River Valley.

November 9, 1999
Six ash venting episodes or small explosions occurred between 29 October- 5 November 1999. Maximum ash cloud height was 10,000 to 12,000 feet. There were no new pyroclastic flow deposits for these events. The seismic network network recorded a total of 115 rockfall signals, 40 volcano-tectonic earthquakes, 71 hybrid and 13 long period earthquakes.

November 5, 1999
On 26 and 27 October, the Soufriere Hills Volcano produced ash venting episodes, small explosions or dome collapse events. New pyroclastic flow deposits were observed in the Tar River Valley. The 26 October event created an ash cloud that rose ~15,000 feet.

October 27, 1999
On 26 October, an ash cloud erupted from the Soufriere Hills Volcano.

August 23, 1999
Week of August 13-20, 1999: Activity at volcano remained low. On August 20th, two minor volcano tectonic swarms were recorded under the volcanic edifice. 50 rockfalls and 84 volcano-tectonic earthquakes were recorded. Unstable masses sit above Gages, Tuitt's and Galway's. Small rockfalls are being produced in these areas.

August 6, 1999
On 3 August, the Soufriere Hills Volcano released an ash cloud that reached 15,000 feet (~4.5 km) above sea level.

July 21, 1999
The Soufriere Hills Volcano erupted on July 20. There was a moderate explosion and a dome collapsed which produced a large pyroclastic flow in the Tar River Valley. The ash cloud rose above 15,000 feet.

July 6, 1999
On 17 June, pyroclastic flows were sourced from the area of the dome above Tuitt's Ghaut. A light ash fall was deposited in Salem and Old Towne. Between 11-18 June, a total of 120 rockfall signals and 20 volcano-tectonic earthquakes were recorded. On 18 June, ash rose to 7,000 feet (~2km) above sea level. On 2 July, an ash cloud rose 15,000 feet (~4.5) above sea level. On 4 July, ash rose to less than 25,000 (~8km) above sea level. Residents of Montserrat are advised to keep listening to the radio for any volcanic alerts.

June 11, 1999
On 5 June 1999, an ash plume rose to at least 12,000 ft (~3.5 km) above sea level. Pyroclastic flows went down the Tar River and Tuittis Ghaut. A new scoop had been eroded into the dome above Tuittis Ghaut, and a new ashy fumarole was visible in the depression. Up to 1 cm of ash had been deposited in Salem and Old Towne.

January 20, 1999
A pyroclastic flow travelled down the Tar River valley and reached the sea. A large ash cloud from the event was blown to the northwest by strong winds. Further dome collapse could occur at any time, as the dome remains unstable.

January 15, 1999
A small explosive event occurred at Soufrierre Hills, sending an ash cloud to at least 15,000 ft. Light ash fall affected areas to the northwest, including Salem, Old Towne and Olveston. No pyroclastic flows were observed from this event.

 
January 13, 1999
There was a violent eruption of Soufriere Hills volcano at 6:30 am on January 13. A vertical ash column rapidly rose to heights of 20,000 feet (~6,000 m). A great amount of thunder and lightning occurred within this cloud. Ash from this plume fell to the west over the area from Cork Hill to Plymouth. A pyroclastic flow from the event moved down the Tar River valley to the sea. Steam clouds were created as the flow contacted the water.

 
November 12, 1998
The largest collapse of the dome since July occurred on the morning of November 12. Pyroclastic flows were sent down Gages valley, the White River Valley, and the Tar River Valley. Flows down the Gages Valley flowed through Plymouth and reached the sea. Other lobes from this flow spread into the Amersham area, and burning was seen in the port area. The flows down the Tar River Valley also reached the sea. Flows down the White River Valley reached the coast and spread out over the new fan. An ash cloud from this event reached 25,000 ft (7500 m) and showered ash over the entire island. Further collapses from the dome are expected.

 
November 2, 1998
Further dome collapse on November 2 sent pyroclastic flows down the Tar River Valley and into the White River. The flows down the Tar River Valley reached the sea. An accompanying ash cloud reached 10,000 ft (3000 m) and drifted west.
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October 31, 1998
Another small dome collapse occurred, sending ash falls into populated areas north of Montserrat. Pyroclastic flows were produced in the White River and Gages valley. Larger dome collapses in the Galways area are possible in the near future.
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October 26, 1998
A small collapse of the dome occurred on October 26, sending pyroclastic flows down the Tar River and White River valleys. Flows down the Tar River Valley reached the sea. These flows also reached the Tar River Estate House. Ash from this event fell as far north as St. Peters. Ash clouds reached 20,000 to 25,000 ft (~6,000-7,500 m) high. About one inch of ash fell on Richmond Hill.
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October 20, 1998
A dome collapse occurred, sending pyrocalstic flows down Gages Valley towards Plymouth. This pyroclastic flow stretched about 2 miles (~3 km) from the edge of the dome. A plume rose above the volcano and produced thunder and lightening. Ash from this plume fell in Old Towne and areas to the south.
 
 
October 18, 1998
Another partial collapse of the dome today led to additional pyroclastic flows and an ash cloud reaching 7000 ft (~2000 m).
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October 12, 1998
A partial collapse of the northern side of the dome on Soufrierre Hills Volcano caused pyroclastic flows in two valleys on Montserrat. An associated ash cloud reached heights of 25,000 ft (~7500 m). Ash from this event also fell on the western side of the island in the areas of Cork Hill, Old Towne, Olveston, Salem and the Belham Valley.
 
 
July 3, 1998
Major activity at Soufrierre Hills Volcano on Montserrat began at about 3 a.m. on July 3rd. Intense earthquakes for three to four minutes led to a major dome collapse. This collapse produced pyroclastic flows for over two and one half hours. Most of this flow activity occurred in the Tar River valley. Pyroclastic material was deposited throughout the entire river. This material reached the sea, increasing the size of the Tar River delta. Ash fell over the entire island, as well as nearby Nevis and St. Kitts. An ash plume reached heights of over 45,000 ft (14,000 m). Heavy rains around noon caused mudflows from the volcano for about 30 minutes. Around 2 p.m., activity began again. This time three to four minutes of seismic activity led to a small explosion from the dome. A dark ash plume rose 10,000-15,000 ft (3,000-4,500 m) above the volcano. This ash moved west over Salem, Old Towne and Olveston. The volcano is still very dangerous, and further explosions and pyroclastic flows down all sides of the volcano are possible.
December 26, 1997
A major eruption occurred on the morning of December 26 when the dome on Soufriere Hills Volcano collapsed. Most of the material from this collapse traveled down the White River. A large and destructive pyroclastic cloud moved down the White River with the flow. This cloud moved over the villages of Morris, Reids, St. Patricks, Trials, and Fairfield. Two explosions occurred shortly after the dome collapsed. The ash plume from this event reached 36,000 ft (11,000 m).
 
 
November 27, 1997
Large, slow moving pyroclastic flows occurred over Galways Wall on November 27. These flows reached the new fan at the end of the White River but did not enter the sea. There is still danger of continuing pyroclastic flows and renewed explosive activity.
 
 
November 11, 1997
A large dome collapse sent pyroclastic flows down the White River Valley on November 4. This flow reached the sea. The dome collapse lasted for more than one hour and contributed about 70 million cubic feet (2 million cubic meters) of material to the flow. The ash cloud from the flow reached 10,000 ft (~3000 m). Steam and ash venting has continued from the dome. Fumaroles also continue vigorous venting on the northern face of the dome.
There was another dome collapse on November 6. Pyroclastic flows from this collapse also traveled down the White River and reached the sea. The ash cloud from these flows reached 15,000 ft (~4500 m) and was blown west.
Activity at the volcano has decreased since these events, but the area is still very dangerous. Additional dome collapse and renewed explosions could occur at any time.
 
 
October 28, 1997
No explosions have occurred at Soufriere Hills volcano on Montserrat in the last eight days. However, a new lava dome began to grow on the volcano on October 22. It stands well over 250 ft (80 m) above the northeastern crater edge and is growing at a rate of 280 cubic ft (8 cubic meters) per second. On October 28, earthquake activity began to increase drastically at the volcano. This indicates that new explosions and pyroclastic flows could be near.
 
 
October 2, 1997
Three more explosions occurred over the last 24 hours. Each of these explosions were followed by pyroclastic flows down all sides of the volcano. Flows of pumice and ash reached the sea through the Tar River valley and White River valley. They also reached Farms, Dyer's and Plymouth. The large amount of material deposited on the volcano during this activity allows each subsequent flow to travel farther. Eruption columns rose to heights of 20,000 to 40,000 ft (6000-12,000 m) after each explosion. Ash and pumice clasts up to almost 1 inch (~2 cm) in diameter has fallen on inhabited areas of Montserrat from these explosions.
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October 1, 1997
Over the last week, explosions have been occurring at Soufriere Hills Volcano about every 9 hours. Three explosions occurred on October 1. Each was followed by large pyroclastic flows, and accompanying ash clouds were blown over populated areas. These flows moved down the Tar River Valley nearly to the sea and down Tuitt's Ghaut to Trant's. Ash clouds reached heights of 20,000 to 25,000 feet (6,000-7,500 m) and blew to the NW and out to sea. Ash and gravel sized rock fell over populated areas to the north. Ash venting was seen after all three explosions.
 
 
September 26, 1997
Two more explosions occurred after 8:00 pm on September 25. Both led to pyroclastic flows down Gages Valley. The first was heard over much of Montserrat and dropped ash and pumice particles on the northern part of the island in populated areas. Pieces of rock up to 1 inch (2 cm) in diameter fell on parts of the island.
The second explosion generated an ash plume 10,000 ft (3000 m) high. This explosion dropped ash and rock fragments in Old Towne and pumice clasts as far north as St. Johns.
 
 
September 25, 1997
A total of five explosive events have occurred at Soufriere Hills volcano in Montserrat over the last two days. These explosions have generated ash clouds over 10,000 ft (3000 m) high with one reaching 20,000 ft (6000 m). The wind has blown most of the ash and other particles to the west, but if the wind switches to the north, populated areas of Montserrat could be showered with this material. Large pyroclastic flows have accompanied each of these explosions. During one event, collapse of the vertical ash column generated pumice flows.

 
September 23, 1997
The eruption of September 21 that destroyed the airport also wiped out any buildings remaining in Bethel and devestated Tuitts' and Spanish Point. In light of this destruction and the fact that the dome doesn't seem to have lost significant volume from these flows, the British government is considering using force for the first time to remove people from exclusion zones.
Elton John, Paul McCartney, Sting, Eric Clapton, Mark Knopfler and Phil Collins all performed at a concert in London on September 15 to benefit the victims of the volcanic eruption on Montserrat. The concert was shown on pay-per-view television on September 20 and was hoped to have raised around $1.6 million for relocation and new housing.
 
 
September 21, 1997
A large pyroclastic flow buried part of the airport runway on Montserrat and set the terminal on fire on September 21. The flow traveled 3 1/2 miles (5.6 km) to the airport and into the sea. Many fish and lobsters were found washed up on shore after the flow heated the water to dangerously high temperatures. Thick ash also was dropped across the entire island. The government of Great Britain has vowed $64 million to replace housing, hospitals and the airport, which has now been totally destroyed.

September 9, 1997
Scientists are now warning that a major explosion at the Soufriere Hills volcano on Montserrat is likely imminent. Over the past two days, several pyroclastic flows have occurred. These flows continue to press farther to the north. Ash associated with these flows was blown by Hurricane Erika northeast to Antigua. This has caused problems for Antigua's airport, and many of its businesses were forced to close. A plume of ash from Montserrat now stretches over 90 miles (165 km) to the northeast.
The Montserrat Volcano Observatory is urging all residents to move as far north as possible immediately. The southern two-thirds of the island is now completely off limits. Over 5,000 residents are now crowded into shelters at the northern tip of the island. The British government has announced a five year plan to rebuild on the northern part of the island. They have also offered $3,840 to anyone who wants to relocate off the island.
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September 3, 1997
An 8 mile (15 km) wide plume of ash is now extending about 57 miles (106 km) southwest of Montserrat. The dome inside the Soufriere Hills volcano is growing at a rate of 6-7 cubic meters per second. This is the most rapid rate of growth of the dome since the eruption began in 1985. A major dome collapse is possible at any time and could trigger major pyroclastic flows and large explosions which could shower the entire island with ash and rock.
 
 
August 30, 1997
Material on the north side of the dome collapsed today, causing several pyroclastic flows down the northern side of the volcano. Most of these flows have occurred in the regions of Gages and Mosquito Ghaut. A fairly large ash cloud accompanied these flows. This cloud reached heights of 7000-10,000 ft (2100-3000 m) and was blown to the northwest. The flows reached the school at Harris village. Continued explosions and flows can happen without warning. Flows are most likely to occur to the northwest, and explosions could shower the entire island with ash and rocks.
 
 
August 25, 1997
The evacuation of Montserrat is continuing very slowly even though scientists warn that a "massive, cataclysmic" eruption is possible on the island. About 4,000 of the original 11,000 residents remain on Montserrat. Many of those who remain do so because they feel the British government has not offered them enough compensation for their losses. Adults have been offered approximately $4,000 and children about $1,700.
 
 
August 19, 1997
From 9:15 last night until about 12:35 this morning, there were continuous tremors and rockfalls and near-continuous ash production. Gas plumes have been common, and occasional minor explosions or ash emissions have been detected.
Longer and more intense explosions may occur, and Montserrat residents are advised to seek shelter under strong roofs and wear helmets or whatever other head protection is available in such a case. After explosions, small rocks and ash are likely to fall, making driving dangerous. Masks should be worn when outdoors too.
Pyroclastic flows are expected on all flanks of the volcano, making entry unsafe into the exclusion zone, including the Belham river valley. People living south of the Nates River were evacuated overnight.
 
 
August 16, 1997
An increase in activity has prompted authorities to expand the exclusion zone and offer residents money and transportation to neighboring islands.
Details such as the exact amount of money to be offered and who will be offered the deal first have yet to be disclosed.
In the meantime, the governor of Montserrat has ordered the evacuation of the towns of Flemmings, Hope, Olveston, and Salem before nightfall, citing a report by the Montserrat Volcano Observatory that the central part of the island is in more danger than previously thought.
Residents were advised to pack extra food, water, medicine and any other personal items they wish to take.
 
 
August 8, 1997
Soufriere Hills volcano erupted again on Wednesday, August 6. Pyroclastic flows from this and past eruptions that have reached Plymouth have virtually destroyed the capital city. Over 80% of the buildings there are either badly damaged or destroyed. The August 6 eruption was explosive enough to shower even the safe zone at the north end of the island with debris. Ash deposits in Plymouth have grown up to 4 ft (1.22 m) thick. Officials have now ordered an evacuation of the central region of the island, once considered safe. Plumes of ash from this eruption have reached heights of 40,000 ft (12,000 m) and dropped ash on the islands of Nevis and Antigua, which are over 25 miles (40 km) away.
 
 
August 5, 1997
There were two periods of earthquake activity on August 5 which ended in violent explosions and large pyroclastic flows. Large vertical plumes were generated from these explosions. Blocks of pumice up to 3 inches (8 cm) in diameter fell around the volcano. Pyroclastic flows travelled down the Tar river valley and into the sea. Flows also travelled down Tuitts and Mosquito Ghauts. Some material overflowed from Mosquito Ghaut into the Farrells Yard area. Ash was generated every 20-30

August 3, 1997
Pyroclastic flows from Soufriere Hills volcano on Montserrat have reached the capital city of Plymouth. Many homes and businesses can be seen burning from several miles away. Fire fighters have been unable to stop these flames which threaten to consume the entire city. Flows in Gages Valley have also caused fires in Gages Village. These flows generated ash plumes which reached elevations of over 15,000 ft (4500 m). Ashfalls occurred in Isles Bay, Ole Towne, Salem and several other areas west of the volcano.
In the wake of this event and a June 25 event which left 10 dead and nine others missing, the British government is considering permanently relocating all of Montserrat's citizens off the island.


Information supplied by: http://volcano.und.nodak.edu