Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 17 January
to 16:00 18 January 1997
The current alert level is ORANGE

Rockfall and seismic activity have been the most prominent events at the volcano during the past 24 hours. The overall level of activity is judged to be at about the same level as yesterday. Visual observations revealed that the system is replenishing the scar left by the recent pyroclastic flows with new material..

A total of 42 rockfall signals, 14 hybrid and 17 volcano-tectonic earthquakes have been recorded in the last 24 hours. Two long period and a near regional earthquake also occurred Most of the volcano tectonic events happened between 7:00 to 9:00 this morning. At least three of these events were at depths of about 7 km beneath the crater.

Cloud cover prevailed at the upper summit of the volcano today. Visual observations were therefore restricted. From the ground at Whites the dome appeared to be quiet for most of the day. The few rockfalls that were seen occasionally, originated in the upper reaches of chute of the December 11 dome. This was confirmed by the GPS team that made several trips to the upper summit stations by helicopter. The rockfalls travelled to the base of the dome. Another feature that was also observed was fresh growth of material near the vicinity of the scar left by Thursday morning's pyroclastic flow. A high level of steam venting was concentrated near the upper base of Chances Peak.

The reoccupation of the GPS networks continued today. The campaigns were focused on the Chances Peak, Hermitage ,Perches ,Whites and Farrells stations. The results will be processed at a later date. No COSPEC nor gravity measurements were taken today.

The south-eastern part of the dome remains in an unstable state, and further pyroclastic flows will occur in the next few days. A major collapse of the dome is possible. Should this occur, another explosion similar to that of September 1996 could result. It is however expected that there would be several hours of high level pyroclastic flow activity before any explosion. Zone E, which includes Cork Hill and the airport, remains safe.

Montserrat Volcano Observatory