KINGSTOWN, St Vincent (CMC) — Another large explosion occurred at the Soufrière volcano late on Tuesday night with scientists saying the volcano has now begun to generate pyroclastic density currents (PDC).

A bulletin issued by the Seismic Research Centre (SRC) of the University of the West Indies (UWI) said that the explosion occurred at 11:00 pm (local time) and that seismic activity at the volcano which erupted last Friday had changed with explosive activity earlier during the day on Tuesday.

It said prior to the explosion, long-period  earthquakes had been increasing in number.

“Categorized as a vulcanian explosion, it was accompanied by larger seismic tremor which was followed by over three hours of smaller continuous seismic tremor,” the SRC said of the earlier activity.

It said vulcanian explosions are small to moderate explosive eruptions, lasting seconds to minutes and that ash columns can be up to 20 km in height and PDCs can be generated.

“The explosions pulsed for ~30 minutes and produced PDCs that reached the sea at the mouth of the Wallibou approximately six km from the volcano. Once this tremor had died down, long-period  earthquakes were recorded, again slowly growing in numbers, but are significantly smaller than those prior to the 6:30 am explosion.”

The SRC said eyewitness account of this flow indicated that it had extended  further into the sea when it reached the coastline and that observations made later from the coastline indicated that PDCs resulting from the morning have reached the sea  in every valley extending from Larikai to Wallibou.

“The volcano continues to erupt explosively and has now begun to generate pyroclastic density currents. Explosions and accompanying ash-fall, of similar or larger magnitude, are likely to continue to occur over the next few days,” the SRC added.