Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 on 19 November
to 16:00 on 20 November 1995

One hundred and eight (108) earthquakes have so far been located during this period; due to the high number of earthquakes recorded overnight, a six hour period of data remains to be analysed. Most of these events were situated beneath the Soufriere Hills Volcano, in the depth range 0-2.5 km (ie within 1.5 miles of the surface). The quantity of located earthquakes has increased again since yesterday due to a twelve hour period of relatively intense earthquake activity which coincides with a regional earthquake recorded at 19:54 on 19 November The magnitude of the earthquake is 3.5 ion the Richter Scale. The local earthquake swarm died out at about 07:00 on 20 Nov, and seismicity has been relatively quiet since that time.

All of the EDM lines were revisited today. None of the lines showed movements greater than 5 mm since their last occupations. Present shortening rates on the Tar River and Chances Peak lines are well below levels of concern; their constant monitoring will ensure that any changes are rapidly noted.

GPS (Global Positioning System) surveys continue to be carried out each day. Results from 18 Nov show essentially no change from readings on the previous several days for the lines from Reid's Hill to St George's Hill, Reid's Hill to Tar River and Tar River to St George's Hill. The GPS receiver from Reid's Hill will be taken to Chances Peak in the morning to collect data for the day; this re-occupation should verify the relatively large change in line length reported on 18 November.

Scientists shall continue to maintain the same level of vigilance in monitoring. An upgrading of the seismic network will occur tomorrow with the installation of a station at South Soufriere Hills.

Montserrat Volcano Observatory