Montserrat Volcano Observatory

Daily Report
Report for the period 4 pm 18 June
to 4 pm 19 June 1997
The current alert level is ORANGE

Volcanic activity has been low today.

The level of volcanic activity has been relatively low since yesterday afternoon. Activity started to increase at about 6.45am this morning and was slightly elevated for about 5 hours However, activity then declined again to a low level for the remainder of the period under report. The small rockfalls and small pyroclastic flows which did occur were confined mainly to Mosquito Ghaut and the Tar River valley.

The volcano was viewed from Windy Hill late last night by a field team from MVO. A break in the clouds allowed almost the whole dome to be seen, revealing two main active sources for rockfalls, both high on the dome. One was feeding material into the Tar River valley, the other, on the northwestern face of upper dome, was the source of rockfalls channeled into Mosquito Ghaut. From this activity it was inferred that the dome continues to grow. The mountain has been obscured by cloud today.

A team entered Paradise River valley today to obtain samples of Tuesday night's pyroclastic flow. Some pumiceous blocks were recovered, and ash in the deposit was found to degas and become fluidised when agitated with a spade. The pumiceous nature of the blocks and the behaviour of the ash are both indicative that this pyroclastic flow involved a fairly gas-rich magma. Despite having been deposited more than 48 hours earlier and there having been heavy overnight rain, the flow deposits were exceedingly hot, and one team member suffered slight burns when ash blew into his boot.

The seismic activity today has been similar to that of yesterday, with rockfall signals dominating: there were 193 of these in the last 24 hours. The level of earthquakes remained low, with no volcano-tectonic earthquakes, 2 hybrid event and 5 long-period earthquakes recorded.

Electronic distance measurements and COSPEC observations were being undertaken this afternoon.

Further pyroclastic flows and surges could travel into Gages valley, Mosquito Ghaut, Tuitt's Ghaut or the Tar River valley at any time. The authorities and MVO advise that access to Plymouth is restricted for the time being. Zones A and B, which include Tuitt's, Bramble, Bethel, Spanish Point, Farms, Harris and Trants, are extremely dangerous and nobody should go into this area at all.

Bramble Airport remains operational, but the public are reminded that it is open only for essential travel purposes.

Dr Paul Jackson of the Seismic Research Unit left island this afternoon after a short visit.

Montserrat Volcano Observatory