Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 13 May
to 16:00 14 May 1997
The current alert level is AMBER

The nature of the volcanic activity changed this morning, with the resumption of hybrid earthquake activity beneath the volcano.

A total of 58 earthquakes were recorded in the last 24 hours, with most of these in the swarm which started at 9:20 am. These earthquakes are quite small, but six were large enough to be located, and they were at 2 - 3 km beneath the crater.

Rockfalls from the dome have continued at a moderate level, with 102 recorded, slightly more than yesterday. The number of long-period earthquakes has been lower than the last few days, with only 19 occurring. Most of the rockfalls and long-period earthquakes were before the hybrid earthquake swarm began.

The volcano has been cloudy for most of the day, and so observations of the dome have not been possible. However, the clouds lifted this afternoon, so that some of the eastern and northern sides of the dome could be seen from Whites. Small, nearly continuous rockfalls were seen from the north face of the dome, and one of the small pyroclastic flows observed was probably triggered by the shaking by a hybrid earthquake.

An attempt was made to measure the distance to the new reflectors installed at Farrells using the EDM instrument, but no return signal was possible. The reflectors will be revisited so that they can be moved to a better orientation.

The change in activity today 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