Montserrat Volcano Observatory

Daily Report
Report for the period 4 pm 30 June
to 4 pm 1 July 1997
The current alert level is ORANGE

Volcanic activity has been lower today with a continuation of the cyclic pattern but at less intensity than over the previous few days. Two more episodes of enhanced activity and deformation have occurred, but only one period of significant pyroclastic flows.

Last evening, there were a few hybrid earthquakes and an episode of tremor between 7 pm and 10 pm. There were some more small earthquakes between 4 am and 5 am, and then another tremor episode which culminated in a pyroclastic flow episode down Mosquito Ghaut and into the Gages valley. Some reports were received of small explosions associated with the onset of these flows, and some thunder and lightning occurred in the associated ash clouds.

The tiltmeter shows a continuation of the same pattern, although the time between periods of higher activity has been longer today. In total, only 9 rockfall signals and 32 hybrid earthquakes were recorded by the seismic network today. No long period or volcano-tectonic events were recorded.

Observations from helicopter flights today showed that the flows of this morning reached Harris' and Gages village. There were also minor flows in the upper reaches of Tuitt's Ghaut and also over the Galway's Wall. Brief views of the dome above Mosquito Ghaut and Fort Ghaut showed that the scar formed by the major flows of last week is now approximately three quarters full, and that there are two small spines in the area of new growth. A large new extrusion was seen on the dome flanks above the Gages Wall.

It seems likely that the cyclic nature of the activity will continue with repeated periods of pyroclastic flows giving rise to ash clouds away from the volcano, and thus people in the safe zones should stay alert and listen to Radio Montserrat. The pyroclastic flows may travel further than before. The current area of pyroclastic flow activity makes Mosquito Ghaut and Gages the most likely pathways, but further flows in Tuitt's, Tar River or White River are probable as well. 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. Access to Plymouth is completely restricted. Zones A and B are extremely dangerous and nobody should go into these areas at all.

The Belham River valley 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.

There is likely to be some re-suspension of ash in the air today especially if it does not rain. Residents and workers are urged to wear a dust mask.

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

Montserrat Volcano Observatory