Strong eruption at Sinabung volcano, ash to 7 km (23 000 feet) a.s.l., Indonesia


A strong eruption started at the Indonesian Sinabung volcano, North Sumatra at 06:20 UTC on July 28, 2021 (13:20 local time). The Aviation Color Code was raised to Red.

According to Sinabung Volcano Observatory, the eruption lasted for about 12 minutes.

Two volcanic ash clouds were observed from the ground, the first to 7 km (23 000 feet) a.s.l., moving WSW, and the second to 5.5 km (18 000 feet), moving S.

A pyroclastic flow was observed through the east-southeast slope, reaching a distance of about 1 km (0.62 miles) from the summit.

The Alert Level remains at 3 (on a scale of 1 – 4), with a general exclusion zone of 3 km (1.8 miles) and extensions to 5 km (3.1 miles) in the SE sector and 4 km (2.5 miles) in the NE sector.

In the event of ashfall, people are advised to wear masks when leaving the house to reduce the health impact of volcanic ash. Secure drinking water facilities and clean roofs of houses from heavy volcanic ash so that they do not collapse.

People who live near rivers that originate at Mount Sinabung are advised to stay alert to the dangers of lahars.

A significant eruption took place at the volcano at 16:35 UTC on June 6.

The eruption lasted for 421 seconds but it was not clearly observable due to fog and clouds.

Three volcanic ash levels were observed at 21:40 UTC — to 9.1 km (30 000 feet) a.s.l. moving WSW, 7.3 km (24 000 feet) a.s.l. moving W and to 4.2 km (14 000 feet) a.s.l. moving N.

The Aviation Color Code was raised to Red at 17:53 UTC and lowered back to Orange at 06:25 on June 7.

Geological summary

Gunung Sinabung is a Pleistocene-to-Holocene stratovolcano with many lava flows on its flanks. The migration of summit vents along a N-S line gives the summit crater complex an elongated form.

The youngest crater of this conical, 2 460 m (8 070 feet) high andesitic-to-dacitic volcano is at the southern end of the four overlapping summit craters.

An unconfirmed eruption was noted in 1881, and solfataric activity was seen at the summit and upper flanks in 1912.

No confirmed historical eruptions were recorded prior to explosive eruptions during August – September 2010 that produced ash plumes to 5 km (16 404 feet) above the summit. (GVP)

Featured image: Eruption at Sinabung volcano on July 28, 2021. Credit: PVBMG


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