This week a team of scientists and technicians from the Carnegie Institution of Washington and the UNAVCO consortium are visiting MVO as part of their work for the Caribbean Andesitic Lava Island Precision Seismo-geodetic Observatory (CALIPSO) project. Funded by the National Science Foundation since 2002, CALIPSO adds to MVO’s monitoring network with strainmeters and Global Positioning System (GPS) instruments at 4 locations around the volcano. MVO works collaboratively with multiple institutions through CALIPSO to maintain the equipment and to process and store the data. The CALIPSO team is here this week to conduct routine maintenance work on the equipment. Additionally, UNAVCO personnel are here to assist in installing two new GPS stations which will be operated collaboratively.

Strainmeters are highly-sensitive instruments that are usually installed in deep holes - about 200 metres underground - to measure strain. Strain is the measure of the expansion or contraction of rock. This can result from pressure changes due to the movement of magma or gas underground. When pressure builds up, the ground around the volcano can get squashed or expand. Strain measurements contribute to our understanding of the volcano’s activity by recording the underground changes at several different locations. Other deformation monitoring techniques such as GPS and Electronic Distance Measurement (EDM) show how the volcano changes on the surface.

Pictured above is the station at Olveston, which houses a strainmeter, GPS device, and seismometer.

A new vent has been observed in the location where ash venting occurred on 23 March 2012. The vent is located in the floor of the 11 February 2010 collapse scar and is immediately south of the remnants of the old English’s Crater wall and southwest of the long-lived hottest fumarole previously identified. It is estimated that the vent is between 30 and 50 metres across.

The photos were taken from a helicopter north of the volcano looking south by Greg Scott, Caribbean Helicopters.

No further ash venting has occurred since 23 March.

Seismic activity at the Soufriere Hills Volcano has returned to a low level following the ash-venting activity on Friday 23 March.

Government House have issued the following press release:

ZONE C TO RE-OPEN

Zone C on the volcanic risk map, which was temporarily closed last week due to an increase in volcanic tectonic earthquakes below the Soufriere Hills Volcano, will re-open for day time entrance from tomorrow, Tuesday 27 March 2012. The normal conditions of entry will apply.

The public are asked to note that no entrance is allowed under any circumstances to Zone V on the volcanic risk map. Anyone found in this zone is liable to be arrested and charged.

Government House

Monday 26 March 2012.

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Information on the Hazard Level System can be found here.

Following two VT swarms on the 22 and 23 March 2012 involving 49 and 54 events respectively, mild ash venting began at Soufriere Hills Volcano at around 8:00 am local time on 23 March. The venting was sourced from the floor of the 11 February 2010 collapse scar, immediately south of the old English’s crater wall and to the west of the long-lived hottest fumarole previously identified (see photo, taken from Jack Boy Hill, looking slightly southwest towards the Feb 2010 collapse scar). Fumarolic activity on the volcano on the morning of 23 March increased markedly and a new steam fumarole was identified on the NW side of the dome immediately behind Gages Mountain.

The ash venting was clearly pulsatory and sent ash to approximately 6000 feet above sea level (3000 feet above the volcano). At its peak, black jets of ash were seen rising a few hundred metres above the floor of the collapse scar. This type of activity is probably ‘phreatic’ in origin and is formed where superheated rock meets groundwater causing the rocks to fragment, generating ash.

VT earthquakes are related to fracturing rocks probably as a result of increases in pressure. It is likely that these pressure increases and the resulting earthquakes are related to uprising magma below the volcano. Similar types of activity have occurred at Soufriere Hills Volcano up to several months prior to restarts in magma extrusion, for example in 2005 and 2008.

This week a group of students and professors from the University of Leeds and the Ludwig Maxmillian University of Munich, led by Dr Jurgen “Locko” Neuberg, are visiting Montserrat as part of their studies. During their visit, the group of nine PhD students and professors has given seminars at MVO on their research, installed additional monitoring equipment, and gathered field data for their research projects. The research topics are varied and include exploring the connections between how magma moves and fragments (forming ash) with the seismic signals and eruptive activity at Soufrière Hills volcano.

Montserrat provides a wealth of data, both from MVO’s well-established monitoring network and from deposits of recent activity, which has significantly contributed to knowledge of volcanic processes. MVO frequently collaborates with professors and students at other institutions in aspects of volcanological research.

Around 5:20 pm (local time) on 9 March 2012, a small pyroclastic flow travelled down the western flanks of Soufriere Hills Volcano down Spring Ghaut. This small pyroclastic flow went about 1 kilometre to the west towards Plymouth before the ash dissipated in a small ash cloud, which rose about another 4000 feet and towards St. Georges Hill out to sea. The event was caught on the camera on Garibaldi Hill (pictured above) as well as on the thermal camera.

MVO’s seismic monitoring network also recorded the event. To the left is a plot of the seismic signal generated by the flow, as recorded from the seismometer at Fergus Ridge. MVO’s seismometers record pyroclastic flows as they occur. The shaking recorded by the seismometers is caused by the material in the flow colliding with the ground as it travels.

There were no precursors to this event. Although activity has generally been low, this event clearly illustrates that Soufriere Hills Volcano is still an active volcano and that pyroclastic flows can occur at any time with little to no warning.

On Friday, 2 March their Royal Highnesses, the Earl and Countess of Wessex visited MVO. The Royal couple spent the day in Montserrat as part of their Caribbean tour for this year’s Diamond Jubilee celebrations. Shortly after their arrival, MVO staff greeted the Royal couple on the Viewing Deck. After a few minutes of chatting with the staff, Prince and Princess Edward and Sophie viewed a video highlighting the history of the current eruption and received a signed copy of “Island of Fire,” MVO and UWI Seismic Research Centre’s photobook. The Royal couple then toured the Operations Room, where they learned about volcanic phenomena and MVO’s monitoring network, observed the volcano through binoculars, and asked lots of questions. The Royals’ visit to MVO concluded with a helicopter ride, where Prince Edward, along with MVO Director Paul Cole, viewed the remains of Plymouth from the air. MVO is pleased to have been a part of the Royal visit and at the interest shown by the Royal couple in Montserrat’s volcanic history and MVO’s ongoing monitoring efforts.