Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 14 May
to 16:00 15 May 1997
The current alert level is AMBER

The nature of the volcanic activity continued to change over the reporting period, with the resumption of hybrid earthquake activity and more frequent occurrence of small pyroclastic flows. There was also a notable reduction in the number of rockfalls and a further decline in long period earthquakes.

A total of 42 hybrid earthquakes and one volcano tectonic earthquake were recorded in the last 24 hours, with most occurring overnight. The earthquakes remain quite small. Rockfalls from the dome have continued at a reduced level, with 49 recorded, while the number of long-period earthquakes fell to 3. There was an increase in the number of small pyroclastic flows that were discharged into Tar River today. The largest occurred at about 7:00 am this morning. It travelled half way down the Tar River valley to the second break in the slope. Some small pyroclastic flows were also seen on the Galways side of the volcano. It was noted that some of the pyroclastic flows from the east were followed by increased gas and steam emissions. These emissions produced roaring sounds that could be heard from Whites and Harris.

During the first half of the day conditions at the summit of the volcano permitted good views of the upper eastern and northern parts of the dome from the helicopter and to a lesser extent from the ground at Whites. Several moderately intense steam plumes obscured the western and most of the southern sections. The views from the helicopter confirmed that the dome has grown bigger and that some activity is currently taking place along the north to north-east sector. At least two small pyroclastic flows were witnessed along that location today. The eastern peak of the dome appeared to be steeper than the last time it was seen and there were a few unstable blocks distributed along the east face. A small scar was left by the pyroclastic flow that occurred on May 13.

Further attempts were made to establish a new EDM triangle using a target at a site located high up on the flank of the volcano at Farrels. The operation is yet to be completed but some progress were made. Plans to install a new tiltmeter and another instrument to record strong earthquake shocks, at Chances Peak, were rescheduled due ashy conditions.

The continued transition in the style of activity demonstrates that the volcano remains active and dangerous. Only essential visits should be made to the evacuated zone, and ash masks should be worn when in the ashy areas. The Tar River and White River valleys are extremely dangerous, as pyroclastic flows can travel down these valleys with no warning. Zone A should not be entered under any circumstances.

Montserrat Volcano Observatory