Montserrat Volcano Observatory

Daily Report
Report for the period 4 pm 15 October
to 4 pm 16 October 1997

There have been five explosions during this reporting period and a number of other long-period earthquakes correlating with ash venting. The explosions are not as powerful as those early in this explosive sequence and are producing relatively minor pyroclastic flows.

Explosions occurred at 10:20 last night, at 2:51, 6:35 and 9:44 this morning and at 2:20 this afternoon. All of the explosions produced steamy ash clouds which drifted eastwards out to sea, and no ash fell on Montserrat. Ash clouds were in the range of 10,000 to 15,000 feet high except for the 6:35 event, which did not produce a tall vertical column. Vigorous ash venting followed each of the explosions.

Pyroclastic flows were produced from all of the explosions except the one at 6:35 this morning. These flows were confined to the upper parts of Tuitt's Ghaut and Tar River.

The seismic network recorded 15 long-period events, 7 vts, and 2 rockfall signals during the reporting period. There was no particular pattern to these events, although several of the lp events were quite large and were associated with ash venting - these are interpreted as minor explosions. The regional earthquake reported this morning was mis-identified on the seismic records.

The wind direction to the east has kept ash levels down in inhabited areas. The amount of ash in the air both in Northern and Central Montserrat is low. Readings are being taken for Central Montserrat in the Olveston area and in Northern Montserrat in the Mongo Hill area. Readings are taken as an average over the period of the report. Peaks in ash levels still occur, and ash masks should be worn routinely in ashy environments such as close to roads, especially when it is dry.

The current trend is for the explosions to be getting less powerful and more frequent. However, there is still a possibility that larger explosions could occur without any changes in the seismicity or other parameters. Therefore all residents of Montserrat are reminded to be vigilant, to avoid entering the evacuated zone and to stay tuned to Radio Montserrat for further information.

Montserrat Volcano Observatory