Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 29 April
to 16:00 30 April 1996

The level of volcanic activity has not changed much during this period, and is the lowest since the present phase of activity started on 03 April. There have been a number of small rockfall events and small ash clouds, none of them as large as those seen on 28 April.

The seismicity is now dominated by short periods of broadband tremor and moderate-sized long-period earthquakes. The duration of the tremor is often less than one hour long, The long period events are located beneath the crater at uncertain depths. In general, the level of activity is similar to yesterdays.

The eastern EDM triangle and a number of GPS lines were measured today. The results of these are not yet available. The height to the top of the dome was measured as 2940 ft. This is 100 ft higher than the last measurement on 19 April.

Visual observations were possible during the afternoon, both from the ground and from the helicopter. The rockfalls are still occurring on the northeastern flank of the dome, with a smaller number on the southwestern flank. The level of steam production was generally high. The shape of the dome does not seem to have changed much over the last 24 hours. There are no new spines.

Initial processing of the COSPEC results confirms that the SO2 production is very low, at between 75 and 150 tonnes per day.

A number of gravity measurements were made today, using a gravimeter brought by the COSPEC team. These measurements will be used as a reference for future, repeated gravity measurements. These can be used to monitor density changes in the magma chamber beneath the volcano.

The volcano still remains in a highly dangerous state, and the scientists urge that visits to the evacuated zone are kept to a minimum. The Tar River, Long Ground and Whites areas are extremely dangerous and should not be entered under any circumstances.

Montserrat Volcano Observatory