Montserrat Volcano Observatory

Daily Report
Report for the period 4 pm 22 August
to 4 pm 23 August 1997

Activity at the volcano continues at a slightly reduced level. Seismicity is dominated by rockfall signals and there was a small pyroclastic flow into Gages valley at 1.27 pm. There was one, small, hybrid swarm over night but the well-defined cyclic pattern of hybrid swarms has broken down.

Over the last 24 hours 67 hybrid earthquakes, 2 long period earthquakes and 48 rockfalls triggered the broadband seismic network. A swarm of 60 hybrids occurred between 9.45 pm yesterday and 0.56 am this morning. The intermittent rock fall activity generates minor ash plumes above the volcano. There have no major ash emissions today.

Further explosions are possible and these may be more intense and longer lived than those already experienced. If explosions do occur, the central zone should be evacuated immediately, and people in the northern zone should seek shelter under a strong roof as soon as possible. After an explosive event, small rocks and ash can be expected to fall anywhere on the island. Ash and falling rocks can make driving hazardous. Ash is present in the atmosphere and dust masks should be worn outdoors.

All ghauts on the volcano are now filled with hot pyroclastic flow deposits. The enhanced pyroclastic flow activity indicates increasingly instability of the dome and further pyroclastic flow activity is anticipated. This makes all of the exclusion zone extremely dangerous. Pyroclastic flows could reach into the Belham river valley. Access to the exclusion zone is completely restricted, and people should stay away from the flanks of the volcano. People should remain vigilant and continue to listen to Radio Montserrat for any announcements.

Montserrat Volcano Observatory