Montserrat Volcano Observatory

Daily Report
Report for the period 6 pm 25 December
to 6 pm 26 December 1997

There was a major eruption of the Soufriere Hills Volcano in the early hours of this morning. During the reporting period a build-up of hybrid earthquakes occurred during the evening of Christmas Day and the earthquakes merged together about 2 am. At 3 am the activity escalated rapidly and a large collapse of the dome occurred predominantly down the White River. There was a very widespread and destructive pyroclastic surge cloud which swept over the ridges around the White River. The pyroclastic surge cloud moved over the villages of Morris, Reids, St Patricks, Trials and probably Fairfield. The visibility prevented a complete evaluation of the northern limit of the surge. The pyroclastic surge cloud also swept around and over the western end of the South Soufriere Hills to a distance of about 1 km to the east of the mouth of the White River. Some material also swept up the northern side of the South Soufriere Hills nearly reaching the top and then descended the river as the Dry Ghaut to the south-east and reached within about 200 m of the sea. Seismic data and observations by police indicated two explosions occurred at 3.15 and 3.25 am following the main collapse.

There were no views today of the dome due to cloud cover and a fuller reconnaissance and analysis of the effects of the eruption will be completed tomorrow.

Between 16:00 yesterday and 16:00 today, a total of 428 hybrid earthquakes, 2 long period earthquakes and 19 rockfall signals were recorded by the broadband system. Following the collapse there have been sporadic hybrid earthquakes throughout the day.

The ash plume from the pyroclastic flow event reached 36,000 feet. The winds were blowing to the west and south so there was very little ash fall in the populated areas. Air quality at all monitoring stations across the island is good today.

People should remain alert and listen to Radio Montserrat for further information as it is possible that such high level activity could recur.

Montserrat Volcano Observatory