Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 08 September
to 16:00 09 September 1996

Activity at the Soufriere Hills volcano during this reporting period has continued at about the same relatively low level as observed during the previous 24 hours.

The seismicity was dominated by the occurrence of volcano-tectonic (VT) earthquakes. Two hundred and seventy (270) volcano-tectonic earthquakes were recorded . These occurred in two swarms today: the first from 00:46 to 04:38 and the second from 12:38 till the end of the reporting period. The VTs for both sequences were again located at shallow depths beneath the volcano. Some of the earthquakes which occurred today afternoon were reported felt in the Richmond Hilll area. The number of recorded rockfalls was 65 and these were mainly small- to moderate-sized events. Two periods of near-continuous rockfall activity were observed from 16:56 to 18:20 yesterday 08 September and 04:40 to 07:55 today. One hundred and five (105) small hybrid earthquakes and 1 small long period earthquake were also recorded. A high-amplitude broadband signal recorded by the Gages seismic station from 07:36 to 07:56 this morning was due to flash flooding in Fort Ghaut. The relatively high background tremor level observed on all seismic stations for the past two days and attributed to the effects of the winds associated with Tropical Storm Hortense continued throughout the reporting period.

Visibility was very poor throughout the day because of low cloud cover and rain.

EDM measurements were not made today because of the low cloud cover and rain. The COSPEC is still out of commission and will be sent to the manufacturers tomorrow for repairs.

Further rockfalls and pyroclastic flows will occur as the lava dome continues to grow within English's Crater, but indications at the moment are that the pyroclastic flows will be confined to the Tar River valley area. Areas affected by associated ashfalls will obviously depend on the direction and strength of the wind at the time. The rainfall will make some ash-coated roads very slippery so extreme care should still be taken when driving in ash affected areas. Dust masks should be worn at all times in ashy environments, and drivers should exercise caution and consideration for other road users.

The Tar River Valley and surrounding areas continue to be extremely hazardous, and should not be entered under any circumstances. We urge individuals who persist in ignoring this advice to think very seriously before making trips to these highly hazardous zones.

Montserrat Volcano Observatory