Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 on 11 April to
16:00 on 12 April 1996

The level of activity at the Soufriere Hills volcano has remained high over the last 24 hours although there hasn't been any large explosions or major ash clouds. Several signals interpreted as representing rockfalls were recorded. Many small explosions were recorded at 19:41, 21:04, 21:22 and 23:19 on 11 April 1996 and 04:34, 06:20, 06:21, 06:39, 07:41, 10:10, 10:15, 15:47, 15:57 and 15:59 on 12 April 1996. Most of the rockfalls and small explosions resulted in small ash clouds. The event at 15:59 on 12 April was the largest since the eruptions of Monday 08 April and generated a small pyroclastic flow in the Tar River Valley area. The associated ash column rose about 3000 ft above Chance's Peak and drifted westward, depositing ash in Upper Gages, Plymouth and surrounding areas.

The seismic records continue to be dominated by frequent, small hybrid earthquakes, which occur at shallow depths within the volcano. The rate of occurrence of these earthquakes has varied from a minimum of 1 to a maximum of 5 per minute.

Viewing conditions were perfect during most of the day. The tall spine which had majestically dominated the Soufriere Hills Volcano skyline has collapsed with most of the material falling towards the southwest part of English's Crater. However, the remnant of this spine, which has several large cracks, is still impressive and is probably just slightly shorter than Chance's Peak. The base of the remnant spine is being constantly undermined by frequent rockfalls from the over-steepened southwestern part of the dome. Dome growth seems to be concentrated in the southwestern, western and eastern parts of the dome as shown by numerous small rockfalls from these areas during the day. Small ash clouds have been associated with these events. The top part of the pyroclastic flow channel in the northeastern dome has a lot of unstable, blocky material which would probably collapse soon. Continuous steam and gas emissions were observed from several areas of the dome.

Measurements have continued today with the new Global Positioning System (GPS) equipment. The data is still being processed and it is hoped that this would give a better understanding of any deformation associated with the volcano.

EDM measurements have also been made on the White's-Long Ground-Castle Peak triangle and the Amersham-Dagenham, Amersham-Amersham and Amersham-Chance's Step lines. Preliminary examination of the results for the eastern triangle show that the changes remain small but are consistent with the general shortening trends seen over the past few months.

The volcano remains in a highly dangerous state, and another explosive eruption could start at any time. The MVO scientists continue to urge people still living in the evacuated zone to leave immediately. Visits to the evacuated zone should be restricted to those that are absolutely essential. The Tar River, Long Ground and Whites areas remain extremely dangerous, and should not be entered under any circumstances.

Montserrat Volcano Observatory