It seemed like events at Soufriere Hills had been heading for a dome collapse for the past few week and sure enough, part of the summit dome collapsed last night, producing pyroclastic flows that reached the ocean along with a 40,000 foot ash column. The report I received from the Montserrat Volcano Observatory offered the following details:
The collapse started at 11:27 pm local time on Monday 28th July 2008 without any precursory activity. Part of the western side of the lava dome collapsed generating pyroclastic flows that reached Plymouth and the sea.
There were also a few explosions from the dome during the collapse, with
the largest at approximately 11:32 pm.
The height of the ash column was estimated at 12 kilometres (40,000
feet) above sea level.