Montserrat Volcano Observatory

Daily Report
Report for the period 4 pm 2 July
to 4 pm 3 July 1997
The current alert level is ORANGE

Volcanic activity has been at about the same level today with a continuation of the cyclic pattern. Three more episodes of enhanced activity, deformation and pyroclastic flow generation have occurred

Activity at the volcano increased gradually after 4 pm yesterday, and a moderate but prolonged ash eruption started at about 6.37 pm. This lasted almost two hours and produced an ash cloud which rose to about 10,000ft. Pyroclastic flows occurred into Mosquito Ghaut and Fort Ghaut. The flows reached no further than 1 km from the dome.

A further period of ash eruption and pyroclastic flow generation occurred from 2.14 am to 4.30 am with pyroclastic flows down Mosquito Ghaut and Fort Ghaut. Some of the pyroclastic flows were initiated by a vertical component, giving rise to convective ash clouds and associated thunder and lightning. Again these flows did not reach further than 1 km from the dome.

The third period of pyroclastic flow activity was initiated at 11:26 am and followed about one hour of low level tremor. This gradually built up to near continuous pyroclastic flow activity down Mosquito Ghaut and Fort Ghaut. Small explosions were reported during the activity, and the ash cloud associated with the pyroclastic flows reached up to 27,000 feet.

The tiltmeter shows a continuation of the same pattern, with the time period between pyroclastic flows being about 8 hours. However, some flows do occur in the intervening period and so no time can be considered as quiet. In total, 72 rockfall signals, 8 long period and 44 hybrid earthquakes were recorded by the seismic network today. No volcano-tectonic events were recorded.

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.

Professor Steve Sparks arrived on the island today for a short visit.

Montserrat Volcano Observatory