Activity at the Soufriere Hills Volcano during this period has been dominated by persistent rockfalls from the eastern and northeastern sectors of the growing lava dome into the Upper Tar River Valley area. This has resulted in the generation of many ash clouds which have been blown on the wind towards the west-south-west. A relatively small amount of this ash was deposited in the Upper Gages, Amersham and Kinsale areas while the bulk of it seems to have been carried out to sea.
Seismic activity has been characterised by near-continuous low to moderate amplitude broadband tremor recorded at the closest seismic stations. Many small to moderate sized signals interpreted as rockfalls have been recorded, the largest of which occurred at 07:09 on 28 April. This event generated a small pyroclastic flow into the Upper Tar River Valley area. Very few of the hybrid earthquakes seen during the past several weeks were recorded.
John Stix and Pierre Delmelle arrived on the island late yesterday 27 April to carry out gas monitoring. Six Correlation Spectrometer (COSPEC) runs were made today from a jeep on the roads around Plymouth. The quality of the data is good and the preliminary results indicate that the level of Sulphur Dioxide (SO2) production is very low. The last COSPEC measurements in Montserrat were made in late August / early September 1995 by the USGS and also indicated very low SO2 levels.
No EDM or GPS measurements were made today.

The level of activity at the Soufriere Hills Volcano is still high and scientists continue to view the situation with grave concern. The MVO continues to urge that visits to the evacuated zone be kept to a minimum. The Tar River, Long Ground and Whites areas are extremely dangerous and should not be entered under any circumstances.

 

closest seismic stations, especially the Gages seismic station. The tremor started around 18:30 on 27 April and is still continuing at the end of this report period. Several rockfalls also occurred. The largest of these was at 06:28 this morning and generated a moderate-sized ash cloud which drifted towards the northwest, depositing ash in the areas around Upper Gages, Plymouth and Fox's Bay. a few signals interpreted as representing possible small explosions were recorded. Very few of the hybrid earthquakes seen during the past several weeks were recorded.
Visibility during the early morning period from both the Observatory and Bramble Airport was moderate to good. Most of the rockfalls were seen occurring off the northeastern flanks of the dome. Bramble Control Tower also reported near-continuous spiral emission of small amounts of ash, possibly from one of the old vents on the northeastern flank of Castle Peak dome. Another major rockfall at 07:09 this morning from the northeastern dome generated a large ash cloud which drifted towards the northwest , depositing ash on Plymouth and environs. A small pyroclastic flow into the upper Tar river valley area was also observed.
Scientists at the MVO still view the situation at the Soufriere Hills Volcano with grave concern and continue to urge that visits to the evacuated zone be kept to a minimum. The Tar River, Long Ground and Whites areas are extremely dangerous, and should not be entered under any circumstances.

Seismic activity at the volcano has declined noticeably during this 24 hours. At the start of the period, the number of small repetitive hybrid earthquakes was increasing slightly and this continued until it reached a peak of about one event every 40 seconds at approximately 20:00 on 26 April. After that time, the rate gradually decreased to about one every three or four minutes at 16:00 on 27 April. The number of small to moderate sized seismic signals interpreted as rockfalls continued to increase up until an episode of low-amplitude broadband tremor between 06:10 and 07:50 on 27 April. There were noticeably fewer rockfall events after that. One small volcano-tectonic earthquake occurred at 15:47 on 27 April and was located in the Amersham-Broderick's area at a depth of 4 km.
The eastern EDM triangle was measured today. The results show that the slow shortening trend seen since the end of November continues. No GPS measurements were made.
Observations have been hampered by poor visibility for much of the day, but many of the rockfall events seen on the seismographs have been accompanied by small ash clouds which drifted into the Upper Gages Valley. The largest rockfalls seem to have occurred between 10:00 and 12:00 on 27 April. A helicopter inspection at around 13:00 on 27 April showed that there had been a large rockfall on the southwestern flank of the dome. Steam production was still high.
Despite the decrease in seismic activity, the level of activity at the Soufriere Hills volcano is still very high and scientists continue to view the situation with grave concern. The MVO continues to urge that visits to the evacuated zone are kept to a minimum. The Tar River, Long Ground and Whites areas are extremely dangerous and should not be entered under any circumstances.

 

The level of volcanic activity has been high overnight, with the small, repetitive hybrid earthquakes continuing at a rate of one per minute until the early morning. Since about 10 pm last night, increasing levels of rockfall have been recorded. At times in the early morning hours the rockfalls were nearly continuous, and produced an ash plume that drifted west to Foxes Bay. During the last hour, the seismicity has been dominated by moderate-amplitude tremor recorded at the closest stations.
The volcano has been cloudy this morning, so no good visual observations have been possible. The dome has been briefly visible from the Observatory, and does not appear to have changed significantly overnight.
The situation at the Soufriere Hills volcano remains very serious, and the scientific team continues to urge extreme caution. Visits to the evacuated zone should be kept to a minimum. The Tar River, Whites and Long Ground areas are at risk from pyroclastic flows that could happen without warning, and those areas should not be entered under any circumstances.

Seismic activity at the volcano continued at the same low level observed during the previous 24 hours until about 10:00 this morning when it increased slightly. The seismicity is still dominated by the occurrence of small, repetitive, hybrid earthquakes at a current rate of one per minute compared to one every two to three minutes before 10:00 this morning. The number of small to moderate sized seismic signals interpreted as rockfalls also increased. The most significant event during the period was a moderate-sized rockfall/explosion at 12:01. This resulted in an ash column which rose to about 4,500 ft above sea level and drifted to the northwest, depositing small amounts of ash in Plymouth and environs. This event also generated a small pyroclastic flow down the Tar River valley area.
No EDM measurements were made today because of persistent low cloud and rain. Seven GPS lines were measured today across the northern and eastern areas of the volcano and the data is still being processed.
Observations of the volcano from the ground and the helicopter have been possible at times during the day. Many rockfalls were observed today and most of these were concentrated in the northeast of the dome. Vigorous steaming was seen from various parts of the dome, especially the south dome.
The level of activity at the Soufriere Hills volcano is still very high and scientists continue to view the situation with grave concern. The MVO continues to urge that visits to the evacuated zone are kept to a minimum. The Tar River, Long Ground and Whites areas are extremely dangerous and should not be entered under any circumstances.

Seismic activity at the Soufriere Hills volcano during the night has continued at about the same level seen during the last few days. Small hybrid earthquakes continue to occur at a rate of about one every two minutes. Several rockfalls also occurred. The largest of these were at 05:26 and 05:35 on 26 April.
Visibility during the early morning from the Observatory was poor.
Scientists at the MVO still view the situation at the Soufriere Hills Volcano with grave concern and continue to urge that visits to the evacuated zone be kept to a minimum. The Tar River, Long Ground and Whites areas are extremely dangerous, and should not be entered under any circumstances.

The seismic activity has been at a low level during the last 24 hours. The small, repetitive hybrid earthquakes have continued, although they are smaller than before and occurring only about once every two or three minutes. A few small rockfall signals were also recorded, but none of them had large explosive components. One volcano-tectonic earthquake was located at a depth of 2 km southeast of the South Soufriere Hills. Some episodes of low-amplitude broadband tremor have been recorded at the Gages seismic station.
Several very small earthquakes have been recorded by the Gages seismic station over the last few days. Another seismometer was installed at Gages last night to confirm that the earthquakes are not the result of instrument malfunction. The cause of these small earthquakes is not known, but appears to be localised in the Gages area. Swarms of similar events have been identified in previous records from the Gages seismic station, especially during July and August 1995.
The eastern EDM triangle was measured today. The line length changes are small and consistent with the trend of 1 mm shortening per day that has been measured since November 1995. Six GPS lines were measured across the volcano today, between the points in the University of Puerto Rico network. The results will be processed overnight. The results from the GPS lines measured during the last two weeks show changes that are within the error of the technique. Further measurements will be required before any significant large-scale deformation of the volcano can be detected.
Observations of the volcano have been possible at times during the day, from the ground and during two helicopter inspections. Fewer rockfalls were observed today than on previous days, and were concentrated in the northeast of the dome. The two spines in the centre of the dome have not changed since yesterday, and several large blocks still remain in unstable positions in the eastern dome. Vigorous steaming was seen from various parts of the dome, especially the south dome, which was also emitting significant amounts of light brown gas this afternoon.

The volume of the dome has been estimated at 10 million cubic metres, following a careful analysis of photographs taken on 18 April. Further measurements from the ground and from recent photographs will now be used to estimate the current rate of dome growth.

 

Despite the lower level of activity during the past few days, the volcano still remains in a highly dangerous state, and further explosive activity and pyroclastic flows could happen with little notice. Therefore, the scientists continue to urge that visits to the evacuated zone are kept to a minimum. The Tar River, Long Ground and Whites areas are extremely dangerous and should not be entered under any circumstances.

Seismic activity at the Soufriere Hills volcano during the night has continued at the same slightly reduced level seen during the day time. Small hybrid earthquakes continue to occur at a rate of about one every two minutes and their size is much smaller than a few days ago. Intermittent low amplitude broadband tremor was recorded at the closest seismic stations. Several rockfalls also occurred and a few signals interpreted as representing possible small explosions were recorded. The largest rockfall/explosion occurred at 22:16 on 24 April. Two small volcano-tectonic earthquakes and a long period event were also recorded but still have to be located
Visibility during the early morning period from both the Observatory and Bramble Airport was poor.
Scientists at the MVO still view the situation at the Soufriere Hills Volcano with grave concern and continue to urge that visits to the evacuated zone be kept to a minimum. The Tar River, Long Ground and Whites areas are extremely dangerous, and should not be entered under any circumstances.