Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 15 December
to 16:00 16 December 1996
The current alert level is ORANGE

The situation at the volcano has remained essentially unchanged during the last 24 hours. Growth of the December dome continues at a high rate, and the dangers from the volcano are still high. The fresh dome growth means that the Tar River and Long Ground areas are at risk from pyroclastic flows. Although the deformation of the Galway's Wall has slowed over the last few days, a sudden failure of the wall could occur and would have serious consequences for areas in zone A/B. Nobody should be in this zone. Zone E remains safe at this time.

Visibility was excellent for much of today. Several inspections of the December 11 dome and the crater area were made using the helicopter. The dome is still growing fast, and the top of the dome was estimated at 2960 ft. The dome has nearly filled the scar left by the explosion in September. A new spine has grown from the top of the dome during the last 24 hours. Yesterday afternoon, much of the dome was seen to be glowing during a late helicopter flight.

A volumetric survey of the new dome area was made from the helicopter this morning. It seems that a section of the pre-September dome has been uplifted during recent weeks, around the area where the new dome is growing. The amount of uplift will be measured more exactly in a future survey.

The level of seismicity was low during the period. There were 11 dome rockfalls, and the number of dome rockfalls has increased since yesterday, as the December 11 dome grows. Also, there were two landslides from the Galway's Wall, showing that slow deformation of the wall is continuing. Ten long-period earthquakes were recorded today- these have not been very common in recent weeks. There was a single small volcano-tectonic earthquake.

EDM measurements were made today on the southern triangle, which measures lines to a reflector on Chances Peak. No changes in the line lengths were detected from the measurements which were made on 4 December

Professor Steve Sparks left today, after working at MVO for 5 weeks. Jean Cristophe Komorowski and Antony Langlais returned to Guadeloupe today. They have been working with MVO staff to study the tsunami (tidal wave) hazard.

Montserrat Volcano Observatory