A high-impact eruption took place at Semeru volcano, Indonesia at around 12:25 UTC on May 16, 2020. The Aviation Color Code was raised to Red. The eruption comes just three hours after a short-lived, high-level eruption at Ibu volcano, Halmahera. The Aviation Color Code for Ibu was also raised to Red.

The eruption ejected ash up to 14 km (46 000 feet) above sea level, drifting east.

"The eruption seems to be ongoing," the Darwin VAAC reported at 12:45 UTC. "Model winds suggest volcanic ash below 6 km (20 000 feet) a.s.l. may move SW at 9 km/h (6 mph). However, low-levels are obscured by the meteorological cloud."

Height and forecast were based on Himawari-8 imagery acquired at 12:20 UTC and model guidance.

The center reported continuous eruption to 14 km (46 000 feet) a.s.l. at 13:40 UTC. "Forecast polygons assume persistent ongoing eruption."

Geological summary

Semeru, the highest volcano on Java, and one of its most active, lies at the southern end of a volcanic massif extending north to the Tengger caldera. The steep-sided volcano, also referred to as Mahameru (Great Mountain), rises above coastal plains to the south.

Gunung Semeru was constructed south of the overlapping Ajek-ajek and Jambangan calderas.

A line of lake-filled maars was constructed along a N-S trend cutting through the summit, and cinder cones and lava domes occupy the eastern and NE flanks. Summit topography is complicated by the shifting of craters from NW to SE.

Frequent 19th and 20th century eruptions were dominated by small-to-moderate explosions from the summit crater, with occasional lava flows and larger explosive eruptions accompanied by pyroclastic flows that have reached the lower flanks of the volcano.

This volcano is located within the Bromo Tengger Semeru-Arjuno, a UNESCO Biosphere Reserve property.