Montserrat Volcano Observatory

Daily Report
Report for the period 4 pm 28 June
to 4 pm 29 June 1997
The current alert level is ORANGE

The level of activity was relatively low last night until just before 10pm when there was a sudden increase in the level of seismic activity. Incandescent material was seen to be ejected to low heights above the crater and a vertical ash cloud was observed.

Activity then decreased to a low level again but picked up at 4.25am when a period of sustained pyroclastic flow activity began. Most of the pyroclastic flows travelled down Mosquito Ghaut but a small amount of material was also observed in Tuitt's Ghaut. The largest pyroclastic flow reached the vicinity of Harris' village at 6.05am. Ash clouds associated with the pyroclastic flows reached heights of over 20,000ft and there was light ashfall on Salem.

By 7.00am the level of activity had again decreased and a helicopter flight revealed that no material had travelled down Fort Ghaut during the period of pyroclastic flow activity. Three houses close to Fort Ghaut were seen to have sustained serious damage during the activity on Saturday morning.

Much of the volcano was clear of cloud during the morning and a large collapse scar was visible on the north side of the dome. It appears that the collapse on Wednesday 25th June removed some of the summit material and most of the northern flanks of the dome. The scar is scoop-shaped with a steep back wall. The lower part of the scar has already started to fill with blocky new material. The area above Gages wall was obscured by cloud and ash today but there appeared to be sustained ash venting in this area.

A hybrid earthquake swarm began this afternoon at about 2pm and was still ongoing at the end of the reporting period. There have been a total of 80 hybrid earthquakes during the last 24 hours and 49 rockfall signals were also recorded.

More pyroclastic flows are expected and these may travel further than before. Much of Mosquito Ghaut and Fort Ghaut are filled with material which will enable the surge component of any flow to spread more easily over a larger area.

The Belham River is very dangerous. It may provide a pathway for further pyroclastic surges and there is also a risk of hot mudflows which may form rapidly if there is a period of heavy rain. Mudflows travel extremely fast and may be near boiling point, they may extend much further along the Belham River valley than the pyroclastic surges.

The pyroclastic flow and surge deposits will remain extremely hot for several days. Residents must not approach, attempt to handle or walk on the deposits because of the risk of severe burning. Access to Plymouth is now completely restricted. Nobody should go into zones A or B at all, this includes all the central corridor.

The airport is closed today and will remain closed until further notice.

Montserrat Volcano Observatory