A high-level eruption with volcanic ash rising up to 7.62 km (25 000 feet) above sea level started at Ulawun volcano, Papua New Guinea at 01:50 UTC on August 3, 2019.
Multispectral satellite imagery detected a new eruption to 15.2 km (50 000 feet) a.s.l. at 09:53 UTC, moving SW.
Imagery acquired 10:15 UTC indicated another eruption which has punched through the tropopause and has become stratospheric with volcanic ash height to 19.2 km (63 000 feet) a.s.l., the Darwin VAAC reported. "Ash is currently moving radially outwards, however, the mean weighted wind direction is northeasterly."
Today's event follows another stratospheric eruption at the same volcano which started at about 22:00 UTC on June 26, 2019, after a few weeks of increased activity. At least 15 000 people were forced to evacuate.
The Rabaul Volcano Observatory (RVO) reported increased seismicity at the volcano and continuous steam/SO2 emission in 24 hours to about 23:40 UTC on June 25. At the time, the eruption was still not observable on satellite imagery.
Continuous ash emissions to 6.7 km (22 000 feet) were observed extending west from the summit at 01:30 UTC on June 26.
A high-level eruption was first reported at 01:55 UTC with volcanic ash rising up to 12.8 km (42 000 feet) above sea level and moving SW. The Aviation Color Code was raised to Red.
Secondary plume to 7.9 km (26 000 feet) a.s.l. was observed at 02:30 UTC.
Satellite imagery indicated new volcanic emission to approximately 16.7 km (55 000 feet) a.s.l. at 05:50 UTC.
"Much of the ash was being blown out to sea, but villages near the volcano had been evacuated, Steve Saunders, a volcanologist at the nearby RVO, said.
The symmetrical basaltic-to-andesitic Ulawun stratovolcano is the highest volcano of the Bismarck arc, and one of Papua New Guinea's most frequently active.
Ulawun volcano, also known as the Father, rises above the north coast of the island of New Britain across a low saddle NE of Bamus volcano, the South Son.
The upper 1 000 m (3 280 feet) of the 2334-m-high (7 657 feet) Ulawun volcano is unvegetated.
A prominent E-W-trending escarpment on the south may be the result of large-scale slumping. Satellitic cones occupy the NW and eastern flanks. A steep-walled valley cuts the NW side of Ulawun volcano, and a flank lava-flow complex lies to the south of this valley.
Historical eruptions date back to the beginning of the 18th century. Twentieth-century eruptions were mildly explosive until 1967, but after 1970 several larger eruptions produced lava flows and basaltic pyroclastic flows, greatly modifying the summit crater.
Featured image: Eruption at Ulawun volcano at 11:20 UTC on August 3, 2019. Credit: CIRA/RAMMB, JMA (SO2)