Visual observations confirm dome growth to be ongoing, but at a much reduced rate. Material continues to be added to the eastern shear lobe, and continually shed from the crumbling front face down into the Tar River Valley. Heavy rain overnight between 16 and 17 April resulted in lahars [mudflow activity] in the drainages around the volcano at 20:00-20:30 and again at 07:00-08:00 ECT. As the dome stands, a significant proportion of the dome material remains in the sector above Tyres Ghaut to the northwest. The amount of material here is sufficient to generate pyroclastic flows and surges capable of impacting on the lower Belham Valley.
Recorded seismic activity has remained very low throughout the period. The seismic network recorded just 8 rockfall signals, 3 long-period rockfall signals and 3 long-period earthquakes.
The sulphur dioxide (SO2) flux rate during the reporting period has been low with an average of 203 tonnes per day for the first four days of the reporting period, in line with the earlier part of this year excepting the pulses recorded during the past two reporting periods. No data is available fro the remainder of the period as the emission plume has been outside the range of the monitoring array. In the last two days the prevailing wind has been light, and from the south resulting in the gas plume moving northwards, or even slightly north-eastwards over Montserrat, and at times a bluish haze [of sulphur dioxide] has been observed flowing down the northern flanks of the volcano.
The alert level remains at 4.
Residents of Montserrat and visitors to the island are advised to tune into ZJB Radio 88.3 or 95.5 FM for up-to-date information on the volcano.
Access to all areas on the lower flanks of the Belham Valley and further south, and south of Jack Boy Hill to Bramble airport and beyond is prohibited at all times (readers are refereed to the updated risk map). The maritime exclusion zone around the southern part of the island extends 4 km off shore from Spanish Point to Roches Yard on the east side of the volcano, 2 km offshore from O'Garras to Sturge Park on the south-west, and 2 km offshore from Isles Bay to Old Road Bluff on the west (maritime risk map).
For further explanations of the volcanic phenomena described, and information about the Soufrière Hills Volcano and the ongoing eruption, please look at the rest of the MVO website.