Sinabung Volcano (Gunung Sinabung)


Sinabung volcano (2451m) is an andesitic volcano built up of layers of viscous lava flows and lava domes together with deposits from pyroclastic flows and surges associated with lava effusion. Four craters trending in a N-S orientation are found at the summit, the last of which (crater IV) essentially forming a scar on the upper SSE flank of the volcano. In 2010, activity was focussed on craters III and IV. The dome building occurring since the end of 2013 is also in this sector and results in pyroclastic flows being directed towards the southeast.


Pyroclastic flow at Sinabung Volcano Nighttime Pyroclastic flow glowing at Sinabung Volcano

Large pyroclastic flow

Pyroclastic flow at night

Sinabung appears to have been largely inactive for over a thousand years since the most recent pyroclastic flow deposits on the SE flank near Bekerah village could be dated at about 1100 years old. The commonly propagated misconception in the press that the last eruption was 400 years ago, appears to derive from the classification of Indonesian volcanoes according to date of most recent activity. Sinabung had been classified as having not been active for 400 years in the sense that no activity had been documented in this period. However, this merely sets the minimum time since the last eruption, not a specific eruption date. The current eruptive cycle commenced in 2010 with several phreatic explosive eruptions resulting in ash clouds beyond 5 km above sea level. The 2010 eruptions are documented by Sutawidjaja et al. 2013 (Indones. J. Geol. 8(1), p.55-61). The ash was essentially composed of mobilized highly altered (non-juvenile material) and was erupted from both craters III and IV, resulting in two adjacent but distinct ash columns as material was forced out either side of an existing dome complex.

First evacuations were ordered around the volcano in 2010. Activity then declined until the volcano reawakened in September 2013 and activity increased over the following months. By the end of 2013, growth of a small lava dome could be observed in the summit region. An overhanging lava lobe developed on the SE side of the dome where a valley offers no topological constraint. Large pyroclastic flows resulting from collapses of parts of this lobe started to descend to the base of the volcanic ediface in January 2014. Flows of up to around 6 km have resulted in a devastation zone to the SE of the volcano.

Towards the end of January, PF activity was lower than during the 13-14 January peak documented on this page and a huge 800 m long and in places at least 50m thick viscous lava flow descended the ravine that had been channelling the pyroclastic flows.


Sinabung volcano with incandescent lava lobe Lava lobe, Sinabung volcano

View from east at night with incandescent lava lobe

Lava lobe under extrusive vent


According to Yoshimoto et al. 2013 (IAVCEI Conference 2013, Kagoshima, Japan, Poster 4W_4D-P14), Sinabung is younger than nearby Toba Caldera and its development can be considered to have occured in two distinct phases. The older phase, largely forming the western part of todays ediface, is composed of lava flows of porphyritic andesites, whilst the younger stage, forming the eastern part of the ediface and the summit domes is composed of lava flows and pyroclastic deposits of porphyritic basaltic-andesite to andesite (Note: Cameron et al. previously suggested that Sinabung was andesitic to dacitic (Geol. Map of Medan Quadrangle, Sumatra, 1982)). The presence of mafic enclaves in the lavas suggest magma mixing in the run-up to eruptions. No, deposits could be found which could be associated with Sub-Plinian or even Plinian eruptions, suggesting that such violent events may not have occured so far in the eruptive history of the volcano.

Much like nearby Sibayak volcano (see Visitor Information section), Sinabung has in the recent past been the site of sulfur mining operations, since the solfataric activity appears to have been persistent in all summit craters during the intereruptive period, and formed sublimate sulfur deposits.


Documentation of Viscous Flow and Lobe Collapse


Extrusion of lava from Sinabung lava dome feeds a SE-oriented extrusion lobe which is effectively a highly viscous slow-moving lava flow. The volcano has yet to build a significant-sized dome such as seen at Soufriere Hills, Shiveluch, Chaiten or Paluweh, to name but a few examples. The narrow summit region is indeed unlikely to be able to support such a large structure. Activity is similar to that sometimes observed at Colima in Mexico.

During the observation period, the lobe largely appeared to be relatively static, yet it was possible to observe motion of the lobe during the build-up to a lobe collapse. Further, the lobe collapse could be observed in rare detail thanks to unusually clear weather at the time.


ANIMATION OF LAVA LOBE MOTION AND COLLAPSE RESULTING IN PYROCLASTIC FLOW:



Large Pyroclastic Flow, Sinabung Volcano, January 13 2014 Large Pyroclastic Flow, Sinabung Volcano, January 13 2014

Lobe prior to collapse

Lobe during collapse


ANIMATION OF NIGHTTIME PYROCASTIC FLOW AND EXTRUSION LOBE COLLAPSE:



Pyroclastic Flows


Break-off of material at the front of the extrusion lobe results in rockfalls and pyroclastic flows. Numerous flows could be documented during the visit to the volcano from 12-18 January 2014, which included a period of unusually intense activity on January 14.

Large Pyroclastic Flow, Sinabung Volcano, January 13 2014 Large Pyroclastic Flow, Sinabung Volcano


Pyroclastic Flow, Sinabung Volcano Large Pyroclastic Flow, Sinabung Volcano, Sumatra


Pyroclastic Flow under grey skies, Sinabung Volcano Pyroclastic Flow under clouds, Sinabung Volcano


Pyroclastic Flow, Sinabung Volcano Twin-lobed Large Pyroclastic Flow, Sinabung Volcano, Sumatra, Indonesia


Pyroclastic Flow, Sinabung Volcano Daytime Pyroclastic Flow, Sinabung Volcano


Pyroclastic Flow, Sinabung Volcano Pyroclastic Flow with incandescent base, Sinabung Volcano


Pyroclastic Flow in sunlight, Sinabung Volcano Pyroclastic Flow in sunlight, Sinabung Volcano, Sumatra, Portrait format Pyroclastic Flow in sunlight, Sinabung Volcano, Indonesia

Pyroclastic flow in sunlight


Pyroclastic Flow in sunlight, Sinabung Volcano Pyroclastic Flow in sunlight passing church, Sinabung Volcano


Tornados on hot PF flowfield, Sinabung Volcano Pyroclastic Flow approaching tornado on flowfield, Sinabung Volcano Pyroclastic Flows with tornado on flowfield at dusk, Sinabung Volcano

Tornados generated on hot PF deposits


Nighttime Pyroclastic Flow Activity (Sometimes Accompanied by Lightning)


During the night, the incandescent material at the base of pyroclastic flows becomes visible. Larger pyroclastic flows were sometimes accompanied by static discharges (lightning). These were clearly visible at night and could be heard as short cracking noises when close to the volcano during daylight. The discharges sometimes emerged from the ash cloud or illuminated it from within. Unlike normal meteorological lightning, the discharges very short and do not appear to involve multiple use of a plasma channel.


ANIMATION OF NIGHTTIME PYROCLASTIC FLOW WITH LIGHTNING:



Static discharge in flow front of pyroclastic flow, Sinabung volcano Static discharge in flow front of pyroclastic flow with glowing base, Sinabung volcano

Static discharges (lightning) near PF flow front (Evening 14 Jan.)

Lightning near PF flow front (Evening 14 Jan.)


Three-pronged pyroclastic flow descending flank of Mount Sinabung at night Pyroclastic flow with lightning, Gunung Sinabung Volcano

Triple-lobed pyroclastic flow (Evening 14 Jan.)

Pyroclastic flow with triple lightning (Evening 14 Jan.)


Glowing footprint of pyroclastic flow, Sinabung volcano New flow approaching Glowing footprint of pyroclastic flow, Sinabung volcano

As PF clouds blow away incandescent deposit becomes visible

Further PF approaching fresh deposits


Nighttime PF at Mount Sinabung Nighttime pyroclastic flow at Mount Sinabung

Pyroclastic Flow (Evening 14 Jan.)

Pyroclastic flow (Evening 14 Jan.)


Nighttime PF at Mount Sinabung, Sumatra Nighttime PF at Mount Sinabung during 2013-2014 eruption

Pyroclastic flow (Evening 14 Jan.)

Pyroclastic flow (Evening 14 Jan.)


Wide-angle view clouds from Pyroclastic flows, Sinabung volcano Wide-angle view clouds from Pyroclastic flows, Sinabung volcano

Wide-angle view following series of PFs

Wide-angle view following series of PFs


Small PF, Sinabung Volcano Minor PF at night, Sinabung volcano

Small PF during night 13-14 Jan.

Small PF during night 13-14 Jan.


Medium-sized Pyroclastic Flow at night, Sinabung volcano Incandescent lava lobe, Sinabung Volcano

Small PF during night 13-14 Jan.

Glowing lava dome during night 13-14 Jan.


Impact of Eruption on Civilisation


The lower flanks and immediate surroundings of Sinabung volcano contain farmland and a number of small villages. All farms in the pyroclastic flow field have of course been destroyed, whilst heavy ashfall, in particular downwind of the volcano during major eruptive events, has smothered crops and overloaded roof structures causing the collapse of many buildings. For example on January 10, 2014, heavy ash fall damaged villages on the NE flank of the volcano. The thin corrugated metal roofs commonly used in the area were often unable to take the load of the ash and collapsed.


Ash cloud looming over landscape, Sinabung Volcano, Sumatra Village NE of Sinabung Volcano covered in ash

Ash cloud looming over landscape

Village NE of Sinabung Volcano covered in ash


Satellite dish covered by ash and vegetation near Sinabung volcano Volcanic ash and grey landscape at foot of Mount Sinabung Satellite dish broken by volcanic ash load

Satellite dish covered by ash and vegetation

Volcanic ash and grey landscape

Satellite dish broken by volcanic ash load


School roof collapsed by volcanic ash load, Sinabung Volcano School roof collapsed by volcanic ash load, Sinabung Volcano behind

School roof collapsed by volcanic ash load

School roof collapsed by volcanic ash load, Sinabung Volcano behind


School roof collapsed by volcanic ash load Damaged school and trees, Sinabung Volcano

Damaged school against backdrop of heavy ash fall

Damaged school and trees


Corrugated roof collapsed by volcanic ash, Sinabung Volcano, Sumatra, Indonesia

Thin corrugated roofs tear easily under weight of ash

Mosque with roof collapsed under weight of ash


Ash on roof Collapsed roof due to volcanic ash from Sinabung volcano

Inside of collapsed house

Ash falls off steeper roofs

Collapsed roof material


Cleaning ash off roof, Sinabung volcano Removing ash from roof, Sinabung volcano

Removing ash from roof

Removing ash from roof


Graveyard under volcanic ash Shrine covered by volcanic ash, Sinabung volcano House under ash cloud

Graveyard under volcanic ash

Shrine covered by volcanic ash

House in shadow of ashing volcano


Layer of hardened volcanic ash on roof Pyroclastic flow behind village, Sinabung volcano

Layer of hardened ash on roof

Pyroclastic flow descending behind village


House and trees damaged by ash fall Cart coated in volcanic ash House and trees damaged by ash fall, Sinabung Volcano

House and trees damaged by ash fall

Cart covered by ash

House and trees damaged by ash fall


Plantation in ash at foot of Sinabung, Sinabung Volcano Trees snapped by volcanic ash load, Sinabung volcano

Plantation in ash at foot of Sinabung

Tree with snapped branches due to weight of ash


Papaya, Orange plants coated in ash, Sinabung volcano Lettuce coated in ash, Sinabung volcano Coffee plant bent by ash, Sinabung volcano

Papaya, Orange plants coated in ash

Lettuce coated in ash

Coffee plant bent by ash


Young orange tree bent by ash, Sinabung volcano behind Banana tree coated in ash, Sinabung volcano Young orange tree bent by ash, Sinabung volcano

Young orange tree bent by ash

Banana tree

Young orange tree bent by ash


Ash falls and is remobilized by wind, Sinabung volcano Palm tree folded by ash, Sinabung volcano Dead frog unable to survive in ash-covered  landscape, Sinabung volcano

Ash falls and is remobilized by wind

Palm tree folded by ash

Frog killed by ash fall


Motorbike coated in ash, Sinabung volcano Loudspeaker coated in ash, Sinabung volcano

Motorbike in ash

Loudspeaker in ash


Further villages were visited which lay SE of the volcano and had been subject to recent ash fall, although with lower intensity. This villages are also directly at risk if pyroclastic flow activity intensifies.


Evacuated Village SE of Sinabung Volcano Village SE of Sinabung Volcano School at foot of Sinabung volcano

Village SE of Sinabung Volcano


Locals ignoring danger in evacuation zone around Sinabung Volcano

Locals in evacuation zone are not bothered by PF in background


Satellite-dishes coated in ash, Sinabung Volcano Pumice on roof, Sinabung Volcano

Satellite dishes with light smothering of ash

Pumice on roof (strange that only seen at one location

but local insisted it came from eruption)


BMX bike coated in ash, Sinabung Volcano Motorbike coated in ash, Sinabung Volcano

BMX bike with ash "icing" stuck in ash layer

Ash-coated motorbike


Bike chain coated in ash, Sinabung Volcano Wheel coated in ash, Sinabung Volcano

Ash-coated BMX bike, detail. Ash was virtually impossible to detach from chain.

Front wheel of ash-coated BMX bike


Cabbage coated in ash, Sinabung Volcano Flowers coated in ash, Sinabung Volcano Oranges coated in ash, Sinabung Volcano

Cabbage coated in ash

Flowers on grave coated in ash

Crops from around volcano are unpopular


Field coated in volcanic ash, Sinabung Volcano Hut with ash on roof and pyroclastic flow behind, Sinabung Volcano

Abandoned field coated in ash

Farmers hut with PF behind


Abandoned field near Sinabung volcano Field covered in ash by Sinabung Volcano with Pyroclastic Flow in Background Harvesting carrots in shadow of volcano with Pyroclastic Flow descending flank

Ash-smothered field

Ash-smothered field

Field slightly further from volcano


During the visit it was apparent that a large number of locals were not respecting the exclusion zone and continued to travel in and out of it or in some cases apparently were living in the zone. This kind of situation has led to fatalities at other volcanoes such as Soufriere Hills. Many of the locals, over 20000, have however been relocated into a network of evacuation centers where the are housed and fed.


Evacuation center near Sinabung Volcano Inside tent at Evacuation center near Sinabung Volcano

One of evacuation centers in Berestagi

Inside tent which is now home for many people


Kitchen at Evacuation center near Sinabung Volcano Supplies at Evacuation center near Sinabung Volcano Administration Office at Evacuation center near Sinabung Volcano

Communal kitchen

Supplies

Administration office


Civilians evacuating area around Sinabung Bus inside exclusion zone around Sinabung Volcano

Recovering belongings from evacuation zone

Human activity deep in evacuation zone continues


Visitor Information


Sinabung volcano lies in the Toba highlands, about 10 km NW of the capital of the Karo regency, Kabanjahe, and about 50km from the major city of Medan which has over 2 million inhabitants. Medan, the capital of northern Sumatra province, has a large international airport and is the most practical starting point for visits to the volcano. Visits to Sinabung can easily be combined with visits of the Toba caldera, site of the largest known eruption in the last 25 million years. The lake which fills the caldera is 100km long and contains a large post-caldera dome complex in its midst. The lesser known Sibayak volcano, which last erupted in 1881 is also found nearby (about 10km N of Kabanjahe) and has interesting geothermal manifestations. It was also the site of minor sulfur mining operations in the past.

Viewpoint for Sinabung Volcano TV crew near Sinabung Volcano

Main viewing hill with temporary visitor infrastructure

TV crew at one of Viewpoints


Path up Sibayak Gas vent roaring Geothermal pool

Approaching Sibayak crater

Roaring gas vent

Bubbling pool


Sibayak volcano, near Sinabung. Yellow Sulfur Crystal deposits Sibayak volcano, near Sinabung. Yellow Sulfur deposits Sibayak volcano, near Sinabung. Yellow Crystalline Sulfur deposits

Crystalline Sulfur Deposits in Sibayak


Lake toba Waterfall at Lake Toba Traditional Village near Lake Toba

Lake Toba, North end

Waterfall feeding into Lake Toba

Traditional Village near Lake Toba


Visitors should be aware that in the most recent eruptions, pyroclastic flows from Sinabung have been channelled in a SE direction towards Kabanjahe. Hence, an extremely large eruption could theoretically present a danger to inhabitants and visitors alike. However, pyroclastic flow deposits of most previous eruptions appear to extend about 5 km from the summit in various directions, extending thus similarly to those already emplaced by the current eruptive episode. Hence, this extent can be regarded as typical for the volcano in recent times and thus unlikely to be significantly surpassed. During the 2013-2014 eruption an exclusion zone has been established for a radius of several km around the volcano. The exact radius and further restrictions in specific areas are adapted to the activity levels at a given time. For the current situation visitors should obtain local advice in particular from the Volcano Observatory.

Sinabung volcano observatory thermal image of Sinabung volcano

Monitoring the seismic data in Observatory

Thermal imaging of Sinabung


Seismic data Sinabung Volcano Seismometer readout, Sinabung volcano

Digital seismic readout

Digital seismic readout




Photovolcanica Full Index