Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 10 August
to 16:00 11 August 1996

Activity at the Soufriere Hills volcano during this reporting period has been dominated by the occurrence of near-continuous rockfalls and pyroclastic flows in the Tar River Valley area. Several of these pyroclastic flows travelled all the way into the sea.

Activity from 16:00 on 10 August to around 07:00 today consisted mainly of small - to moderate-sized rockfalls, with a burst of volcano-tectonic earthquakes during the period 04:30 to 06:00. More than 182 rockfalls, 37 VTs and 29 hybrid earthquakes were recorded although these numbers would obviously be a minimum because of the saturation of the records by the pyroclastic flows. The VTs were located at shallow depths beneath English's Crater. From around 07:00 this morning, a series of near-continuous rockfalls and pyroclastic flows have been occurring in the Tar River Valley up till the end of this reporting period. Two episodes of particularly intense pyroclastic flow activity were observed from 07:05 to 08:50 and from 13:36 to 15:08. Today's pyroclastic flows, which were due to collapses of parts of the eastern flank of the lava dome, resulted in near-continuous ash clouds which were blown westward on the wind. Significant ashfalls occurred in Plymouth, Richmond Hill and Fox's Bay. Smaller ashfalls were reported from St. George's Hill, Cork Hill and Garibaldi Hill. Several of today's pyroclastic flows did reach the sea but there was no overspill beyond the Tar River Valley boundaries. The largest ash clouds around 17:17 today probably reached a height of 30,000 ft and were associated with thunder and lightning. In fact, two aircrafts flying in the region did report seeing the top of the volcanic ash cloud above 40,000 ft.

The level of activity has decreased at around 19:00 this evening. Further rockfalls and pyroclastic flows will occur but these would be confined to the Tar River Valley area. There is no need at the moment for alarm. People in areas affected by ash falls should exercise great care when driving and should wear dust masks.

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