Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 27 January
to 16:00 28 January 1997
The current alert level is ORANGE

A slight decrease in volcanic activity has been observed during the last 24 hours. The recent pattern of two volcano-tectonic earthquake swarms per day has stopped and the level of rockfalls and hybrid events was lower than yesterday's totals. Growth of the lava dome continues to be focused in the south-eastern section of the English's Crater.

Excellent visual observations were possible this afternoon from both the ground and the helicopter. During helicopter inspections, it was clear that the new dome within the scar of January 20 continues to grow on all sides. A few rockfalls were observed from the Whites observation post. The most significant one developed into a small pyroclastic flow at 3:51 pm today which travelled down the north-north-east face of the dome. There were some moderately sized landslides from the outside of Galways Wall.

The swarms of volcano-tectonic earthquakes which have dominated seismic activity recently have stopped. Only 7 volcano-tectonic earthquakes were recorded in this reporting period. There were 19 rockfall signals and no long-period earthquakes recorded, notable reductions from yesterday.

The two cracks on Chances Peak were measured again today. The width of the wider crack is now 23.6 inches while the other 2.1 inches. Over the last two days the wider crack extended by 1.6 inches while the other extended by 0.2 inches. The recent trend therefore continues. A survey of the new dome was made using laser-ranging binoculars from the helicopter.

As the new extrusion in the south-east of the crater continues to grow, it is likely that it will collapse and cause further pyroclastic flows in the next few days. Although the dome is likely to collapse gradually, a larger collapse cannot be ruled out. An explosion similar to that of September 1996 could result in the event of a major collapse. 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