Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 12 August
to 16:00 13 August 1996

The level of 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.

One hundred and seventeen (117) rockfalls, 39 long-period and 42 hybrid earthquakes were recorded. No volcano-tectonic earthquake was recorded. The largest rockfalls, which occurred at 17:11 on 12 August, and 10:37, 10:51 and 12:04 today, were associated with small ash clouds. The events of 10:51 and 12:04 led to pyroclastic flows which travelled as far as the Tar River estate house and the Tar River Soufriere respectively. A large -amplitude broadband signal recorded on the Gages seismic station from around 06:10 and which lasted about 30 minutes was due to flash flooding in Fort Ghaut. Intermittent episodes of low-amplitude broadband tremor were also recorded on the stations closest to the Crater.

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

No EDM measurements were made today because of the poor visibility and rain. COSPEC measurements of the amount of SO2 in the volcanic plume were made today and the data is still being analysed.

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