Montserrat Volcano Observatory

Daily Report
Report for the period 4 pm 09 September
to 4 pm 10 September 1997

Activity at the Soufriere Hills volcano has been at a high level again today, with a number of pyroclastic flows down the northern flank of the volcano. There have also been a number of hybrid earthquakes, mainly in swarms prior to peaks in pyroclastic flow activity. Escalations to this activity could be rapid and involve pyroclastic flows in the Belham Valley or even explosions. All people on Montserrat are thus asked to remain particularly vigilant at this time.

One main episode of pyroclastic flow activity occurred during the reporting period, with flows directed over the northern flanks of the volcano in the Mosquito Ghaut and Farrell's plain area. As this activity was during the night (around midnight), the exact locations and sizes of the flows was difficult to estimate. Ash was distributed over the Salem and Old Towne areas. Smaller pyroclastic flows have been intermittent throughout the day and an episode of intense ash generation was starting at the end of the reporting period.

Good visibility during this afternoon revealed a very steep face to the dome over the head of Mosquito Ghaut which is currently the active growth area and the source of most of the pyroclastic flow activity.

Due to the move of MVO today to its new position at Mongo Hill, there is no precise earthquake count. However, signals from pyroclastic flows dominate the records, and hybrid earthquakes occurred in swarms both during yesterday evening and prior to the pick-up in activity this afternoon.

Given the size of the dome further collapses are likely and these may take place with little or no warning. The collapses need not necessarily be preceded by hybrid swarms. Topography suggests that the Belham Valley may be quickly filled with deposits allowing flows to impact upon Old Towne and Friths areas and associated surges could get to Salem. The southern part of Montserrat is thus extremely dangerous and all areas south of the Nantes River should be evacuated.

If an explosion does occur, small rocks and ash can fall anywhere on the island. People should seek shelter under a strong roof as soon as possible. Helmets or other head protection should be used and it should be remembered that ash and falling rocks make driving hazardous.

Today's ash fall in the central part of Montserrat means that people should wear ash masks when out of doors until the ash has stopped circulating.

Montserrat Volcano Observatory