Montserrat Volcano Observatory

Morning Report
Report for the period 4 pm 24 June
to 7 am 25 June 1997
The current alert level is ORANGE

Volcanic activity continues at a high level, with two more swarms of hybrid earthquakes overnight. The swarms are getting progressively larger, with more earthquakes of larger magnitude.

There is continued deformation of Chances Peak, with the mountain moving small amounts in harmony with the earthquake swarms. In the last two days the automatic extensometer on Chances Peak has shown increased movement of the large crack.

The latest earthquake swarm has just reached a peak, with 4 or 5 earthquakes occurring every minute. At the time of highest activity, the hybrid earthquakes could more accurately be described as continuous tremor. There have been several small pyroclastic flows in Mosquito Ghaut in the last hour. Observations of the dome last night showed that the top of Mosquito Ghaut is the only active area of the dome at the moment, as the focus of activity has switched from the eastern side to the north in the last few days.

Further pyroclastic flow activity is expected, and the high level of activity means that these flows could happen at any time and be larger than before. The current area of activity makes Mosquito Ghaut the most likely pathway, but further flows in Gages, Tuitt's or Tar River are probable as well. Access to Plymouth has been completely restricted as a temporarily measure this morning: the essential services will be allowed access when the activity dies down. Zones A and B are extremely dangerous and nobody should go into these areas at all.

Bramble Airport remains operational, but the public are reminded that it is open only for essential travel purposes. The sirens will be tested as usual this afternoon.

Montserrat Volcano Observatory