Montserrat Volcano Observatory

Morning Update
Report for the period 16:00 15 September
to 07:00 16 September 1996

Volcanic activity overnight has been at a relatively high level. Two short volcano-tectonic earthquake swarms have occurred, separated by a period of high rockfall activity. The first VT swarm occurred between 17:35 and 19:24 yesterday evening and the second between about 02:10 and 04:20 this morning; these swarms are similar to those seen over the previous several weeks and preliminary indications are that these earthquakes are also located beneath the crater at shallow depth (above 2 km). Rockfall activity was highest in the period 20:00 to 22:00 last night shortly after the end of the VT swarm, and several large rockfalls or small pyroclastic flows also occurred soon after the end of this morning's VT swarm.

Visibility during the early morning was poor due to low cloud cover at the volcano. However, several of the rockfalls since dawn have produced small ash clouds visible from the observatory and blowing over the Plymouth area.

Further rockfalls and pyroclastic flows will occur but all indications continue to be that the flows will be confined to the Tar River Valley area. However, areas affected by associated ashfalls will obviously depend on the direction and strength of the wind at the time. Scientists are anticipating enhanced ash generation over the next few days if the dome undergoes partial collapse as expected. Dust masks should be worn at all times in ashy environments.

The Tar River Valley and surrounding areas are extremely hazardous and should not be entered under any circumstances.

Montserrat Volcano Observatory