Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 23 April
to 16:00 24 April 1997
The current alert level is AMBER

The level of rockfall activity has been high during the last 24 hours, with almost continuous rockfalls from the south of the dome during the first part of the reporting period. This has resulted in ash production throughout the first half of the day, with light ash fall to the north-west of the volcano. By the end of the reporting period, activity had dropped down to a lower level.

The broadband seismic network recorded 162 rockfall signals. This is an increase since yesterday, and one of the highest number of rockfalls recorded this year. Most of these rockfall signals have been small and of short duration, but two larger signals at about 5 pm yesterday and 10 am this morning each lasted for about 10 minutes. There were also 16 long-period earthquakes, and no hybrid or VT earthquakes. Although none of the rock-fall or pyroclastic flow events have been as long as those during major collapses, the high frequency is indicative of a significant amount of material eroding from the dome. The level of rockfall activity at the end of the reporting period had reduced relative to the level overnight.

Visibility has been fairly good, and observations were made from the helicopter and from the summit of South Soufriere Hills this morning. Near-continuous rockfalls and pyroclastic flows were seen and heard coming from the dome above Galway's Wall. The pyroclastic flows were small, and the longest run-out distance was about 1.5 km. The dome could not be seen clearly because of the continuous ash production and intermittent low cloud, but a small scar has apparently been formed in the south-western part of the dome. The majority of the rockfalls and pyroclastic flows are now being shed over the western side of the Galway's wall, and a new chute has been eroded into the wall. Most of the recent flows have travelled along the western valley wall and the deposits in this area have been substantially widened. Light ash was blown to the north-west of the volcano.

The alert level is Amber. However, the events of the last 48 hours show that the level of volcanic activity is changeable. Further ash fall in the safe zone is expected, and so residents should always walk with an ash mask. The Tar River and White River valleys are extremely dangerous, and should not be entered under any circumstances.

Montserrat Volcano Observatory