Montserrat Volcano Observatory


Daily Report
Report for the period 16:00 on 25 Jan. 1996
to 16:00 on 26 Jan. 1996


The small, repetitive hybrid events which have dominated the seismicity over the past few days continued throughout the period, although the frequency of occurrence decreased after 18:00 on 25 January to 4 events per minute. Amplitudes have been slightly variable, but the events are still too small to be located by the network. The events are most likely to be occurring at shallow depth beneath the dome area and similar patterns have been seen on several occasions previously during this phase of dome growth. Several other types of seismic signal have been recorded during this period. Two signals were correlated with ash-producing events - the first at 16:41 on 25 January and the second at 11:55 on 26 January. This latter event was witnessed by scientists on the crater rim and comprised a major rock avalanche from the northern area of dome growth.

EDM measurements were carried out on the Long Ground - White's Yard - Castle Peak triangle today. The changes in line length continue to be within the error of the method.

Excellent views of the new dome were again obtained today in clear conditions from the helicopter and from the crater rim at Chances Peak and the new observation position at Farrell's. Active growth continues on both the north and south sides of the dome, with abundant rock falls, some of which produced small ash clouds which drifted to the west. A spine is growing vertically in the south whereas growth in the north appears to be a more general swelling. The growth rate does not appear to have changed significantly over the past few weeks and remains very low. Steam emissions continue from several parts of the crater.


Montserrat Volcano Observatory