Mount Sinabung enters a period of heightened activity

Indonesian Sinabung volcano entered a phase of increased activity several days ago. The volcano has reportedly generated frequent small to moderate pyroclastic flows accompanied with strong vertical explosions.

The pyroclastic flows at the southeastern and eastern volcano slope are currently destroying the new lava lobe which has been growing at the volcano since October 20, 2016.

The intense vertical explosions indicate the internal supply of fresh and gas-rich magma has increased over the last few months, according to Volcano Discovery.

Sinabung volcano eruption, November 1, 2016, 08:26 (local time). Image credit: Endro Lewa

Sinabung volcano eruption, ash devil, November 1, 2016, 08:26 (local time). Image credit: Endro Lewa

On November 1, one explosion and seven pyroclastic flows have been observed in a period of 6 hours. The activity was reported on the east-southeastern flank with run-out lengths between 1 500 and 3 500 m (4 921.3 and 11 482.9 feet) while ash plumes rose to altitudes between 800 and 1 500 m (2 624.7 and 4 921.3 feet).

Some of the pyroclastic flows have reached the areas used by locals, who are being advised to remain outside the exclusion zone, as accidents may occur.

Sinabung volcano eruption, November 1, 2016, 08:26 (local time). Image credit: Endro Lewa

The extrusion process of viscous lava has continued with a slow average pace of the last three years, despite some fluctuations, which suggests the internal activity of the Sinabung volcano has not changed significantly in itself.

The extruded lava accumulates at the summit crater, forming thick lobes on the southeastern upper flank. These masses sometimes crumble as they become unstable, and produce avalanches and/or pyroclastic flows.

The alert level remains at 4, on a 1 to 4 Indonesian scale, signaling the highest caution should be exercised.

Video credit: AFP

On October 5, the Darwin VAAC reported an ash plume, rising to an altitude of 3.3 km (11 000 feet) above the sea level, and drifting southeastward. On October 12, another ash plume rose to 4.6 km (15 000 feet) a.s.l and drifted eastward.

According to GVP, the latest eruption of Sinabung volcano was reported in mid-September 2013 and continued until October 2014. A continuing eruption was also observed from November 2014 through April 2015.

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-high (8 070.9 feet) 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 (16 404.2 feet) above the summit. (GVP)

Featured image: Sinabung volcano eruption, Ash devil, November 1, 2016, 08:26 (local time). Image credit: Endro Lewa