Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 14 August
to 16:00 15 August 1996

Activity at the Soufriere Hills volcano during this reporting period continued at about the same rate as that observed during the previous 24 hours. Also, it was similar in nature, being dominated by signals indicative of small- to moderate-sized rockfalls and several small pyroclastic flows in the Tar River Valley.

Sixty one (61) rockfalls, 14 hybrid, 1 long-period and 14 volcano-tectonic earthquakes were recorded during this reporting period. Several of the largest rockfalls were associated with small pyroclastic flows in the Upper reaches of the Tar River Valley. The period of highest activity was between 11:22 and 12:14 and consisted of near-continuous rockfalls and small pyroclastic flows, with the pyroclastic flow at 11:53 producing an ash cloud with a maximum height of about 5,000 ft above sea level. This and other ash clouds generated during the day were blown westward on the wind resulting in small ashfalls in Plymouth and environs. The VTs occurred in two small swarms from 20:00 to 20:25 on 14 August and 09:59 to 10:39 on 15 August. These events were located at shallow depth beneath English's Crater. A regional earthquake of magnitude 3.5 which occurred about 190 km from Montserrat was recorded at 15:40 today.

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

EDM and COSPEC measurements were not made today because of poor visibility and rain. The COSPEC measurements of 13 August yielded an SO2 flux of 626 tonnes per day.

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