Activity at the Soufriere Hills volcano during this reporting period has been slightly higher than over the past few days. Small rockfalls continue to occur and a number of other seismic signals were also recorded.
Thirteen small rockfalls were recorded during the reporting period. The largest occurred at 21:01 on 25 September. Sixteen hybrid events were also recorded. Twenty one volcano-tectonic earthquakes occurred during the day; these VT's are somewhat transitional with hybrid events, and are the first such events to be recorded since last Tuesday. Low amplitude broadband tremor was recorded throughout the reporting period; this increased in amplitude after 13:20 this afternoon.
Visibility was relatively good all day, although the top of the dome was obscured. Some red-hot rock and high temperature gases were seen in the bottom of the scar, suggesting fresh magma is getting close to the surface again, although material falling from the walls of the scar is covering any new dome which might be forming.
EDM measurements were conducted on the lines between Amersham and Amersham and between Chance's Peak Steps and Amersham; the results of this survey are not yet available.
MVO scientists expect that rockfalls and possibly pyroclastic flows will occur during the next few days as the unstable sides of the new scar feature at English's Crater stabilise. All indications are that the rockfalls and pyroclastic flows will be confined to the Tar River valley area. Dust masks should be worn at all times in ashy environments, which may persist for some time as ash dries out and blows around. Drivers should exercise caution and consideration for other road users, especially when driving through areas still affected by ash or gravel.
The extensive damage which occurred in the Long Ground area last week demonstrates the extreme danger which individuals subject themselves to if they venture into this area or beyond into the Tar River valley. The Tar River and Long Ground areas are now extremely hazardous and we urge individuals who persist in ignoring this advice to think very seriously before making trips to these potentially deadly zones.
Bennett Simpson of BGS left island today after a month-long tour of duty at MVO working on seismological aspects of the eruption. Prof Steve Sparks returned to the island late this afternoon - he will be here for about two weeks undertaking research work in close collaboration with MVO.