MOSCOW (Sputnik) – Thousands of were evacuated due to eruption of Ulawun volcano in the southwestern part of the island of New Britain in Papua New Guinea, media reported on Thursday.
The country’s government estimates that at least 5,000 people have left the villages located near the volcano, which began spewing ash on Wednesday morning, the Radio New Zealand broadcaster reported.
The activity at the volcano seems to have decreased a lot or ceased last evening at the end of the very violent eruptive phase.
Satellite observations show that the impressive umbrella cloud topping out and spreading as a circle more than 150 km diameter in the lower stratosphere rather quickly dissipated when the eruption column stopped feeding it.
VAAC Darwin has still a warning in place of ash plumes at up to 55,000 and 45,000 ft altitude (flight levels 550 and 450) as the attached picture shows, but expects the ash to dissipate during the next 12 hours or so.
A reason why the ash from Ulawun seems to leave the atmosphere much more quickly than the ash from last week’s large explosion at Raikoke in the Kuriles is likely its larger average grain size as the magma during the eruption at Ulawun was probably more fluid (less viscous), which allowed the manifestation of lava fountains observed in the beginning and causes fragmentation to much coarser ash (sub-millimeter to millimeter range), which fall out from the air more quickly.