A moderate pyroclastic flow occurred in the Tar River valley last night, which was the largest pyroclastic flow in the Tar River since 20 January. The event began at 8:40 pm, with a continuous low-amplitude seismic signal which gradually increased in intensity. It reached a maximum at about 9:20 pm, and declined thereafter, with the activity ceasing at 9:50 pm.
No observations of the flow were possible, but MVO observers at Harris' Lookout saw the ash cloud, and some glowing from the dome. The ash was carried to the west by the wind, and an estimate of the height of the ash cloud was not possible.
The observers at Harris also heard intermittent roaring sounds, which are thought to be due to vigorous steam venting from the dome. There have been reports of roaring sounds being heard by several people, including MVO workers at the crater rim, in the last few days, and these reports indicate there has been a change in the way the dome degasses.
Since the cessation of pyroclastic flow activity, the volcano has been quiet, with a few small rockfall signals and hybrid and long-period earthquakes.
The top of the volcano remains obscured by low cloud cover. An inspection of the Tar River valley will be carried out by helicopter later this morning.
Whilst dome growth continues at the Soufriere Hills volcano, it remains dangerous. Last night's pyroclastic flows indicate that the activity can increase suddenly, without warning, and pyroclastic flows and surges are likely in the Tar River and White River valleys. People should stay well away from these areas. Visitors to Zone C should equip themselves with protective gear and stay alert.