Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 3 July
to 16:00 4 July 1996

There were slight changes in the level of activity at the Soufriere Hills Volcano during the previous twenty-four hours. Small rockfalls from the lava dome and the occurrence of moderate sized hybrid earthquakes continued to be the dominant features. Views of the crater area revealed that a huge slab had been extruded at the top south-eastern section of the dome. Several large isolated blocks could also be seen at various locations along the slopes of the dome.

A total of fifty two rockfall events were recorded today, slightly less than yesterdays count. The largest events occurred at 21:59 on July 3 and at 02:09 and 11:44 on July 4. A small ash cloud was seen emanating from the crater area after the latter event. Long period earthquakes remained low, with five recorded over the reporting period. The daily count of hybrid earthquakes, on the other hand, continues to rise, with 25 events recorded today. Continuous low amplitude broadband tremor occurred from about 12:00 midnight to 07:00 am this morning and from about 1:00 pm to 3:40 pm this afternoon.

A brief period of excellent viewing conditions today enabled observations of the dome from the ground and the helicopter. The most interesting development observed was a huge slab that had been extruded at the top south-eastern section of the lava dome. This slab had a vertical crack down the middle and activity was generally concentrated around its base. Several large loose bolders were also seen at various locations on the slopes of the dome. A small quantity of fresh dome material, mainly blocks were seen in the upper reaches of Fort Ghaut. Steaming and gas production appeared to be occurring at a moderate level from several areas.

EDM measurements were taken today but the results are not yet available. Gravimetric surveys were carried out again today. The three new stations that were established yesterday reproduced the same results today.

Mr. Stephane Sol and Dr. Simon Young left Montserrat today. Mr. Sol had been involved in the EDM surveys during their stay on island. Dr. Young had been involved in several aspects of the monitoring effort at the MVO.

The Soufriere Hills Volcano is still highly dangerous to people and property on it's eastern and upper western flanks. Visits to the evacuated zone must be kept to an absolute minimum. The Tar River, Long Ground and Whites areas to the east and upper Fort Ghaut, Gages Village and Upper Amersham areas to the west are all extremely dangerous. All access roads to these areas remain closed and people should not enter these areas under any circumstances. If they do, they put themselves and others at direct risk of serious injury or death.

Montserrat Volcano Observatory