Montserrat Volcano Observatory

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

Volcanic activity has continued at a high level, with two further explosions from the lava dome, with associated pyroclastic flows and ash clouds. The explosions are thus far smaller than those in early August, but that is not to say that they will remain that way, and the volcano remains in an extremely dangerous state.

The third and fourth explosions of this series were at 8:42 last night and at 7:23 this morning. Both produced a vertical eruption column rising to more than 10,000 feet and pyroclastic flows which descended valleys on the northern flank of the volcano. Flows from the explosion this morning also went down the Gages valley. Flows are produced from the dome by collapse, aided by the explosion which gives flows extra energy. Visual reports of the explosion last night are vivid, with red hot rock blown high into the air close to the dome.

Some flows have continued to enter the upper part of the Belham valley with surges over-topping the valley sides. As material fills the valley, successive flows are likely to travel further and thus threaten areas previously not threatened. Ash and rock from today's explosions was carried out to the west by the strong winds so did not impact upon inhabited areas.

Over the last 24 hours 33 hybrid earthquakes, 9 volcano-tectonic earthquakes and 8 rockfalls triggered the seismic network. Explosion signals are very similar to those seen in August, although the precursor hybrid earthquake swarms are not as well defined. At the time of writing, a hybrid swarm continues.

Scientists are anticipating further explosions and these may be larger than before. If the wind direction changes then clasts could fall on Salem and areas further north. Pyroclastic flows and surges from the explosions are very mobile and threaten all of those areas in the exclusion zone. Pyroclastic flows can also occur between explosions, and these could be large enough to reach to the Belham Bridge or beyond. These flows move extremely fast and you cannot get out of their way.

The volcano is in a highly dangerous state and everyone still in the exclusion zone is encouraged to move north as quickly as possible. Those remaining in that area do so at great risk. If the sirens sound, move north and to higher ground immediately, taking a hard hat or cushion for protection from falling clasts.

Montserrat Volcano Observatory