Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 13 August
to 16:00 14 August 1996

Activity at the Soufriere Hills volcano during this reporting period was similar to that observed during the previous 24 hours. It was dominated by small- to moderate-sized rockfalls and a few small pyroclastic flows in the Tar River Valley.

Eighty two (82) rockfalls, 31 hybrid, 4 long-period and 37 volcano-tectonic earthquakes were recorded. Four of the largest rockfall signals at 16:36 on 13 August and 14:34, 15:02 and 15:20 on 14 August were associated with pyroclastic flows in the Tar River Valley and ash clouds which were blown westward on the wind. The pyroclastic flow at 15:20 travelled to within 100 m of the sea while the ash cloud generated by the event at 15:02 reached a height of about 7,000 ft above sea level. Ash from these flows fell in Plymouth and environs. The volcano-tectonic earthquakes occurred in two sequences from 20:25 to 21:55 on 13 August and from 07:57 to 09:02 on 14 August. They were located at depths less than 2km beneath English's Crater. Intermittent low-amplitude broadband tremor was recorded at the stations closest to the crater throughout the reporting period, with the most persistent episode between 19:41 and midnight of 13 August. The Gages seismic station also recorded a flash flooding event in Fort Ghaut from 16:01 to 16:23 on 13 August.

Visibility was generally very poor throughout the day, with the volcano obscured by low clouds and rain.

EDM measurements on the eastern triangle were made today but the data is still being processed. No COSPEC measurements were made today.

Further rockfalls and pyroclastic flows will occur but all indications are that these will be confined to the Tar River Valley area. However, areas affected by associated ashfalls will obviously depend on the direction and strength of the wind at the time. People in areas affected by ash falls should exercise great care when driving, especially since rainfall has made roads very slippery. Dust masks should be worn in ashy environments.

The Tar River Valley and surrounding areas are now extremely hazardous, and should not be entered under any circumstances. We urge individuals who continue to ignore this advice to think very seriously before making trips to these highly hazardous zones.

Montserrat Volcano Observatory