Montserrat Volcano Observatory

Morning Update
Report for the period 16:00 04 September
to 07:00 05 September 1996

Activity at the Soufriere Hills volcano during the night continued at about the same level as observed during the previous reporting period. However, the number of small -to moderate-sized rockfalls and small pyroclastic flows recorded was lower but two vigorous sequences of small- to moderate-sized volcano-tectonic (VT) earthquakes did occur. Preliminary calculation of locations for these volcano-tectonic earthquakes indicate that they are occurring at shallow depths beneath English's Crater. These VTs indicate that magma is still forcing its way to the surface from shallow depths as the process of dome growth at the Soufriere Hills volcano continues. Low-amplitude broadband tremor was recorded intermittently at the seismic stations closest to the Crater. A large-amplitude broadband signal recorded only on the Gages seismic station from 05:12 to about 06:00 was due to flash flooding in Fort during the heavy early morning rains.

The dome was not visible during the early morning period because of low cloud cover on the volcano.

Further rockfalls and pyroclastic flows will occur but all indications at the moment are that the pyroclastic 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. The rainfall during the night would not have completely washed away the ash so extreme care should still be taken when driving in ash affected areas. 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