Montserrat Volcano Observatory

Daily Report
Report for the period 4 pm 27 June
to 4 pm 28 June 1997
The current alert level is ORANGE

A hybrid earthquake swarm began at about 4pm last night and had ended by 6pm. The earthquakes were mostly small and the swarm was not very intense. The level of seismic activity remained low until about 11.30pm when another hybrid earthquake swarm began. This swarm included larger earthquakes and was more intense, it lasted until about 2am in the morning.

At 3.51am there was a strong seismic signal which is considered to have been a small pyroclastic flow in the Gages area. Since then the level of seismic activity has remained low with occasional rockfall signals.

On Saturday morning, there was a prolonged period of eruptive activity, lasting more than one and half hours, which produced copious amounts of airborne ash, several small pyroclastic flows into Mosquito Ghaut, and a moderate pyroclastic flow in Fort Ghaut. The latter flow reached as far as Webbs Estate - Ryners, just above the hospital. All the flow material remained within the ghaut but did ignite some vegetation and rubbish. As far as could be seen, there were no houses damaged by the flow.

Volcanic activity continues at an elevated level following the large pyroclastic flows on Wednesday afternoon. The volcano exhibits a cyclical pattern, with pulses of magma reaching the surface about every eight hours. Some of these pulses, however, produce only slightly enhanced activity in the crater.

The big dome in the northern part of the crater, which dominated the mountain until Wednesday, is now known to have been significantly reduced in height and size by the violent eruption on that day. However, the large void formed by the collapse is being infilled rapidly.

In its present style of eruption, further pyroclastic flows can be expected. These may run further than before because the upper parts of both Mosquito Ghaut and Fort Ghaut are now partially filled, and surge components might therefore spread more readily over a wider area. Any flows down Belham River could effect the sides of the valley, including Corkhill.

The high level of activity makes areas around Mosquito Ghaut, Fort Ghaut, Tuitt's Ghaut and Tar River dangerous in the extreme. The Belham River valley is also very dangerous and should not be entered. Access to Plymouth has been completely restricted this morning. Zones A and B are extremely dangerous and nobody should go into these areas at all.

The existing pyroclastic flow and surge deposits will remain extremely hot for several days. Residents must not approach, attempt to handle or to walk on the deposits because of the risk of severe burns. In the event of heavy rains, the flow deposits can become remobilised into mudflows at near boiling temperatures and these too could cause burns to anyone in their paths.

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

Montserrat Volcano Observatory