Montserrat Volcano Observatory

Daily Report
Report for the period 16.00 21 May
to 16:00 22 May 1997
The current alert level is ORANGE

Volcanic activity remained at a relatively low level with regular rockfalls and small pyroclastic flows until about 3.00pm today when a period of sustained, elevated volcanic activity began.

During the early afternoon the cloud partially cleared on the dome, the western side was particularly clear due to a shift in the wind direction to the north west. Rockfalls were observed on the eastern, northern and western flanks of the dome. At 1pm some rocks were observed falling into Tuitt's Ghaut following a rockfall on the north eastern flank of the dome. Two or three spiny structures were observed on the upper northern flanks of the dome and a substantial number of rockfalls emanated from this area.

A period of sustained, elevated activity began at about 2.30pm with regular pyroclastic flows generated from the upper parts of the dome and flowing mainly to the north. From about 3pm there has been almost continuous ash generation from the volcano with a vertical plume observed on several occasions emanating from the summit of the dome. Ash has fallen on Salem sporadically throughout the afternoon, 1mm-sized rock fragments were reported falling at Farrell's and ashfall was reported in St Johns in the north of Montserrat.

A total of 27 hybrid earthquakes were recorded during the last 24 hours two of which generated rockfalls. There were also 23 long-period earthquakes, 18 of which generated rockfalls. Three volcano-tectonic earthquakes were recorded during the late morning and there was a total of 67 rockfall signals.

A tiltmeter was installed on Chance's Peak today and data from the accelerometer installed on Chance's Peak on Sunday was downloaded. An EDM survey was also completed today to the north of the volcano.

The volcano is in a dangerous phase, with the possibility of pyroclastic flows breaking into the northern ghauts. Dome growth continues and an escalation in the level of activity remains possible. The Tar River valley, Long Ground, White's and Tuitt's areas are very dangerous, and should not be entered because of the dangers of pyroclastic flows. Nobody should enter zones A and B, and only essential visits should be made to the evacuated zone. Ash masks should be worn when in the ashy areas.

Montserrat Volcano Observatory