Montserrat Volcano History

Here is a Brief Chronology of Eruptive Events of the Montserrat Volcano

On July 18 1995, ash and steam venting was first observed at the Montserrat Volcano. Activity was largely confined to the NW flank of Castle Peak lava dome which was formed in the 17th century in "English crater" (a 1km wide crater left by a massive collapse event during an eruption about 4000 years ago (Roobol and Smith, 1998. Geophys. Res. Lett. 25, p.3393-3396).

Largely phreatic activity continued at the Montserrat Volcano, reaching a first climax in a large phreatic explosion on August 21st which threw ash over much of Plymouth and initiated a first evacuation. Signs of dome growth were observed at the Montserrat Volcano in the NW sector of the dome towards the end of September 1995.

Pyroclastic flows were first observed on March 29, 1996, in Tar River Valley (TRV). On the 12th of May, PFs reached the sea and this happened repeatedly in the following months for the Montserrat Volcano. By July, extrusion rates reached 10 cubic meters / sec and repeated small dome collapses accompanied by large pyroclastic flows were observed. On 17 September 1996, a series of dome collapses was followed by a massive magmatic explosive eruption with a 13km high ash column.

Over 500000 Tonnes of ash fell on Montserrat from the volcano. Dome growth restarted for the Montserrat Volcano in December of that year.

On March 30, 1997, PFs flowed southwards into White River valley, near the Montserrat Volcano destroying the touristic sites of Galways Soufriere and Great Alps waterfall. Increasing PF activity to the N and NE culminated in PFs reaching to within 50m of Blackburne Airport during a partial dome collapse on the 25 June 1997. These flows also destroyed the settlements of Streathhams, Riley, Harris, Bramble, Bethel, Spanish Point, Trants and Farms.

Although these had been officially evacuated, 19 fatalities were recorded from the Montserrat Volcano. On 1 July 1997, a PF reached the Catholic Church in central Plymouth. Further flows of the Montserrat Volcano destroyed parts of Plymouth on the 3rd and 4th. A major PF flowed through the center of Plymouth to the port on the 3rd of August
From the 4th to 12th August, numerous vulcanian explosive events resulted from the Montserrat Volcano ash clouds up to 13km high. Column collapses of the explosion clouds were observed with associated pumiceous PFs. On 21 September, a major dome collapse resulted in PFs which reached the sea at several points to the E and NE of the Montserrat Volcano and set fire to the terminal building at Blackburne airport.

These led to the complete destruction of Tuitts, Bethel and Spanish Point. Further about 10-hourly vulcanian explosions occurred between September 22rd and October 21st with column heights of over 10km. On 4 November 1997, a southerly oriented dome collapse sent PFs down White River valley to the sea.

Smaller PFs had reached the sea at this point in the previous month.Montserrat Volcano needs to be closely monitored. Destruction of many settlements at the SW side of the volcano occurred on 26 December 1997, when a highly energetic PF surge probably associated with a lateral blast blew many houses off their foundations in the St Patricks and Morris settlements near the White River valley and set fire to many houses nearby.Montserrat Volcano

Montserrat Volcano Erupting

In 1998 The Montserrat Volcano witnessed a period of dome degradation with only sporadic minor activity. Occasional collapses of the dome continued to generate PFs.

Passage of Hurricane George in September caused massive lahars which swept huge amounts of loose volcanic debris down the flanks of the Montserrat Volcano, burying parts of Plymouth and other locations in up to several meter thick deposits. Further periods of heavy rainfall in November and December had a similar effect on the Montserrat Volcano.

Dome degradation for the Montserrat Volcano continued into 1999, with a large collapse event throwing ash up to 12km on the 20th of July. At the end of November, renewed dome growth was observed for the Montserrat Volcano.

By February 2000, small PFs were reaching the sea down Tar River valley as the new dome gained in stature. A first major collapse of the new dome on the Montserrat Volcano occurred on 20 March 2000 during a period of heavy rainfall, with much of the dome making its way down Tar River valley. This was followed by vulcanian explosions and inevitable lahars. Dome growth resumed shortly afterwards for the Montserrat Volcano.

Continued growth in 2001, resulted in the volume of the dome for the Montserrat Volcano reaching a record 162 Million cubic meters by the end of July. On the 29th of July, during a period of heavy rainfall, 45 million cubic meters of the East flank of the Montserrat Volcano dome collapsed over a period of 8 hours, resulting in near-continuous PFs down Tar River valley into the sea.

A smaller collapse of the North side of the Montserrat Volcano dome occurred on 4th October with several PFs again reaching the sea. On 14 October, outer parts of the Montserrat Volcano dome on the SE gradually collapse, producing continuous low energy PFs down Tar River valley into the sea over a 6 hour period. On December 28th a small collapse of the North East side of the dome produced PFs lasting for over an hour and flowing into the sea.

On January 12, 2002, an energetic flow down the Tar River valley was accompanied by a 2-3km ash column and an over 1km high steam column at the point of sea entry. In February, PFs continued to reach the sea and an extruded spine on the top of the Montserrat Volcano dome was measured reaching up to 1080m (90m above the rest of the dome).

Heightened PF activity was observed in the following months. On September 29, a minor Montserrat Volcano dome collapse sent PFs into the sea near Spanish point. On the 8th December a further larger collapse (5 Million cubic meters) sent energetic PFs to the same area and filled much of White Ghaut.

Montserrat Volcano dome growth and PF activity continued into 2003, culminating in a major collapse event on 12/13 July. The Montserrat Volcano collapse was the largest to date, involving 210 million cubic meters of Montserrat Volcano dome material. Ash clouds reached a height of 15km and massive PFs reached the sea down Tar River valley resulting in secondary phreatomagmatic explosions which generated hot base surges that spread inland along the coast up to the Spanish Point area, burning vegetation in the area (Edmonds and Heard, 2005. Geology 33(4), p.245-248).

Much of Montserrat was coated in a thick layer of ash. This was followed by 3 vulcanian explosions on 13, 14 and 15 July, throwing ash and lithics up to a height of 12km. After a period of intense ash venting on 1 August, Montserrat Volcano dome growth ceased and activity remained low for the rest of the year.

The only notable event in 2004 for the Montserrat Volcano was a collapse event on March 3rd. Ash clouds reached an altitude of 7km and PFs reached the sea down Tar River Valley.

The early part of 2005 remained uneventful until increased seismic activity in May and June, accompanied by some ash venting and was followed by two explosive events on June 28th and July 3rd, the first of which producing PFs into the sea at Tar River, and both producing about 6km high ash clouds. On August 5th, signs of renewed dome growth for the Montserrat Volcano were visible. Minor PF activity occurred in the following months for the Montserrat Volcano.

The first major collapse of the new Montserrat Volcano dome occurred on May 20th, 2006. Most of the 90 million cubic meters of the Montserrat Volcano dome collapsed over a period of under 3 hours. Seismic activity attributable to rockfalls and PFs increased in the early hours of the morning, and by 6:45 PFs were flowing down Tar River valley to the sea by the Montserrat Volcano.

At 7:40, a huge explosion of the Montserrat Volcano threw an ash cloud to a height of 17km and large ballistics rained down on the flanks of the Montserrat volcano. Massive PFs flowed to the sea by the Montserrat Volcano generating a base surge which spread north along the coast and set vegetation on fire as far as the Spanish Point area (as in July 2003).

Vigorous ash venting continued for much of the day and rainfall caused massive mudflows down all sides of the Montserrat volcano. By May 23rd 2006, a new lava dome could be observed in the crater. On June 06th, a small collapse of the Montserrat Volcano dome occurred, once again sending PFs to the sea via Tar River valley. On the August 29th, PFs reached the sea and ash clouds reached an altitude of 10km.

From August 31st to September 10th, several episodes of vigorous ash venting occurred from a vent located between the Montserrat Volcano dome and Gages wall. Small PFs from N to E of dome were observed in following months as activity started to shift to the N.

On Jan 28th 2007, explosive activity on the Montserrat Volcano accompanied by a 10km high ash cloud was reported. Importantly, a large PF was able to flow NW along the Belham River valley. This PF had a run-out of 5km, a new record for this side of the Montserrat Volcano. Numerous smaller PFs were observed to the North of the Montserrat Volcano dome. During April 2007, the Montserrat Volcano dome which had reached the huge volume of 208 million cubic meters ceased growing.

On July 20th 2008, a significant increase in volcano-tectonic tremors was detected at Soufriere Hills. Ash venting and small PFs were observed during the following days. At 23:27 on 28 July a notable eruptive event started with little warning, culminating in a series of explosions, the most powerful being recorded at 23:38. The resulting ash column reached an altitude of over 10km and PFs flowed down Tar River Valley, White River Valley and most notably into Plymouth and Lee´s Yard.

While the TRV flow mainly consisted of older material resulting from partial Montserrat Volcano dome collapse, the other flows were pumice-rich suggesting that they resulted from partial collapse of the eruption column. Fist-sized pumice fragments also fell in inhabited areas NW of the Montserrat Volcano.

The PF heading into Plymouth split into 2 lobes which reached the old police station and Pentecostal church, respectively. Several buildings (including the Pentecostal church) were set alight by the flows. This activity marked the beginning of a further phase of low-level lava extrusion focussed in the area of the explosion crater.

An explosive eruption of the Montserrat Volcano occurred on 02 Dec 2008. This scattered large ballistics up to 1km from the Montserrat Volcano dome and was accompanied by large pyroclastic flows on the W flank of the volcano and an ash cloud reaching over 10km in height.

The PFs inundated the Lee's Yard area and flowed through Plymouth into the sea, setting fire to several buildings on the way. The PF deposits were mainly of older material, suggesting that they had resulted from partial collapse of the Montserrat Volcano dome. Associated surges burnt vegetation to near the top of St. Georges Hill of the Montserrat Volcano. Further explosions occurred on Dec 3, 4 and 5.

Activity at the Montserrat Volcano dome increased in mid-december with extrusion and intermittent ash venting from multiple vents occurring on the southwest side of the dome. Several medium-sized PFs were observed.

Signs of extrusion on North and West flanks were additionally reported a few days later and activity continued to increase until the end of the month with medium-sized PFs entering Tyers Ghaut, Tar River Valley and Plymouth. On Jan 3rd 2009, following a period of increased seismic activity, two powerful explosions resulted in plume heights of over 10km.

Both were associated with column collapses which caused pumiceous PFs that entered Plymouth. Activity dropped off rapidly after these events and no significant activity was reported until October 2009.
Renewed activity commenced with vigorous ash-venting events occuring in the period 4-7 October.

By 9 Oct. renewed dome growth was visible and pyroclastic flow activity commenced. Due to the central location of the extrusions, flows were observed in numerous drainages during the following month, with some reaching the sea down White River valley at the south end of the island of Montserrat.

Due to heavy rainfalls, numerous Lahars entered Belham River Valley. Activity gradually shifted to the west of the former pre-2009 Montserrat Volcano dome structure, forming a new Montserrat Volcano dome nested on the side of the older one.

Pyroclastic flow activity consequently focussed to the west with moderate-length PFs primarily flowing between Gages and Chances Peak in the direction of Plymouth, and also spilling into Spring Ghaut with larger ones flowing some distance into Aymers Ghaut. In mid-december several PFs reached the sea via Whites Bottom Ghaut.

On Jan. 8th 2010, a vulcanian explosion occurred resulting in fountain-collapse PFs in numerous drainages and notably Belham River Valley, where the flows reached to within 300m of the former bridge. Vegetation along Paradise Ghaut in the vicinity of Harris also appears to have been Two further weaker vulcanian events followed on Jan. 10.

On Janurary 18th a sustained small dome collapse on the west flank resulted in PFs which passed Gages and Spring Ghaut into Aymers Ghaut where they continued into the sea and buried the lower parts of the abandoned settlement of Kinsale. The end of January saw flows reaching the sea again through Tar River valley.
At the beginning of February, activity was largely focussed on the west flank with a vulcanian explosion on Feb. 5 again resulting in large PFs into Aymers which extended as far as 500m to sea.
Following a shift in activity to the north two days earlier, a major collapse event occured on Feb. 11. The sustained collapse event lasted nearly an hour and involved several pulses.

This was the largest event since May 1996 and involved mobilization of approx. 20 million cubic meters of Montserrat Volcano dome material. Voluminous PFs flowed NE and reached the sea over a significant length of the east coast, in particular inundating the area of the abandoned Blackburne (Bramble) airport, which has been completely buried (indicating a local deposit depth of at least 10m), and extending the coastline by about 300m (max. 650m) in this region.

Surges inundated Streatham (where several houses were razed to their foundations) and Windy Hill and overtopped the ridge W of Harris village, flowing into the Farm River Valley. Pictures kindly provided by Greg Scott of Caribbean Helicopters reveal that the low-lying parts of Harris were completely destroyed by energetic flows, whilst surges burnt all vegetation at the Harris Lookout area, but the houses there remain standing.

A large collapse scar was left on the north side of the Montserrat Volcano dome and additionally a new crater formed in the summit region. The latter may have been the source of the explosions which discharged pumice clasts and resulted in emplacement of several pumiceous pyroclastic flows.
First signs of renewed extrusive activity have been reported after the Feb. 11 collapse event and it is possible that significant activity will resume.

The huge pre-2009 Montserrat Volcano domes stability is likely to have been compromised by the renewed activity and a catastrophic Montserrat Volcano dome failure could occur with little warning, posing a major threat to anyone entering the exclusion zone.

A significant collapse of the Montserrat Volcano dome could result in events even surpassing the Feb.11 event and could involve large PFs entering Plymouth or Belham River Valley, in the latter case threatening many until now unscathed properties. (last update Feb.22 2010).