Soufrière Hills volcano (Montserrat), activity update: medium-sized pyroclastic flows
During the past week, Montserrat's volcano has been more active again and produced pyroclastic flows that may have reached the sea.
The following is the original MVO weekly report:
<<On 29 August, there was an episode of pyroclastic activity during which flows may have reached the sea down Tar River valley and a steam and ash cloud was reported moving east at 30,000ft. In addition, heavy rain caused mudflows in all drainages around the volcano. <br>On 30 August small pyroclastic flows were highly visible on the northeast and south flanks of the lava dome. At about 3am on 31 August two noisy, vigorous ash and steam vents opened on the west and north flanks of the lava dome. The tremor associated with this activity is still ongoing so we assume the vents are still active though they are obscured by thick cloud. This ash venting episode is clearly audible from Salem and the surrounding areas.
The seismic network recorded 588 rockfall signals, 41 long period rockfall signals, 61 long period earthquakes, 30 hybrid earthquakes and 12 volcano tectonic earthquakes during the reporting period. Relative to the last reporting period, seismicity is characterized by a large increase in rockfall events. Average sulphur dioxide flux for the reporting period was estimated at 351 tonnes/day, varying between 79 tonnes/day on 25 August and 1720 tonnes/day on 30 August.
The alert level was raised to 4 on 31 August. Residents of Montserrat and visitors to the island are advised to tune into ZJB Radio for up-to-date information on the volcano. Access to all areas south of Richmond Hill, and south of Jack Boy Hill to Bramble airport and beyond is prohibited at all times. The daytime entry zone, comprising the top part of St. George’s Hill, is open from 6 am to 6 pm. The maritime exclusion zone around the southern part of the island extends 3 km off shore from Whites Yard to Roches Yard on the east side of the volcano, 2 km offshore from O’Garras to Gingoes on the south-west, and 200 m offshore from Plymouth.>>