Ulawun volcano (Papua New Guinea): ash cloud warning still in place, but ash seems to dissipate quickly
Чт, 27 июн 2019, 06:1106:11 AM | ПЇЅПЇЅПЇЅПЇЅПЇЅ: T
The activity at the volcano seems to have decreased a lot or ceased last evening at the end of the very violent eruptive phase.
Current ash cloud forecast for the remnant ash ejected during the major eruption of Ulawun volcano yesterday (image: VAAC Darwin)
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.
Thu, 27 Jun 2019, 02:45
Вулкан Ulawun: Консультативный центр по вулканическому пеплу: VA OBS TO FL550 MOV NW AND TO FL450 MOV E AT 27/0200Z.
Wed, 26 Jun 2019, 20:45
Вулкан Ulawun: Консультативный центр по вулканическому пеплу: VA OBS TO FL550 MOV S AT 26/2000Z OBS VA DTG: 26/2030Z