Montserrat Volcano Observatory

Daily Report
Report for the period 6 pm 7 November
to 6 pm 8 November 1997

Today seismicity has remained at an elevated level with ash venting continuing during the reporting period. There was a pyroclastic flow at about 4:20 am today which deposited very fine ash on the north eastern side of the island. Another flow much smaller was recorded today and observations revealed that both events occurred on the Galways side and down the White River and the material from the 4:20 event entered the sea.

The hybrid swarm which started at about 7:30 yesterday evening continued until 2 o'clock this morning. Since that time the seismicity has been dominated by high amplitude tremor - which continues at the moment but from about 4:30 pm today the amplitude of the hybrid earthquakes have increased slightly and the events seen are now very discreet, occurring at a rate of about two per minute. The tremor amplitude has also decreased slightly. As has been the case recently, this tremor has similar frequency content to hybrid earthquakes and so can be assumed to also be related to gas escape from the magma. In the 24 hours before 4 o'clock this afternoon 40 hybrid earthquakes, 23 long period earthquake and 1 rockfall triggered the seismic network.

Excellent observations of the scar formed by collapse of the lava dome yesterday afternoon were made today. A significant amount of re-growth of dome material has already occurred and the scar formed as a result of collapse from the Galways side of the dome been refilled by that new growth in the form of a steep sided stub of dark blocky material. A lot of steam and ash venting was also seen in pulses coming from behind the stub, which is also surrounded on all its sides by steep faces.

Throughout the day the volcano has been venting ash. Because of an unfavourable wind direction fine ash has been blown as far north as St Johns. Despite this the 24 hour average level of ash in the atmosphere in central and northern Montserrat was low today with values of 17 micrograms per cubic meter at the MVO and 35 micrograms per cubic meter in the Olveston area.

With the tremor continuing as it is another pyroclastic flow can be expected soon. There is no guarantee that such a flow would go down the White River again, it could easily come down Farrells plain instead, in which case there is a danger of pyroclastic flows moving down the Belham valley. There is also a chance that the volcano will start exploding again. Stay tuned to Radio Montserrat for further information.

Montserrat Volcano Observatory