Mount Sinabung


This Indonesian volcano, which you’ve probably seen on the news, used to be one of the quiet ones.

For 1,200 years those living near Sinabung saw nothing more than occasional steaming at the summit.

That’s why boffins put the little volcano on their B list, when the era of scientific monitoring arrived, and focused limited resources instead on the country’s problematic A-list fire mountains.

Then, one day in late August 2010, this happened:



Within two days, a network of seismic stations surrounded the mountain, which soon had its own volcano observatory, too. (H. Gunawan et al.)

However, as Sinabung commenced a VEI 2 eruption, local communities and resorts were devastated.

Ashfall was a serious problem, but Sinabung also turned everyone’s lives upside down.

No one locally had ever had to deal with an active volcano before.

There was confusion at first as thousands evacuated out from under mile-high gray plumes that rained ash and volcanic rock down on them, their homes, and their fields.

Fortunately, the gentle people of Indonesia are surprisingly tough. The nation’s 70-plus other volcanoes have also given them lots of experience in handling such emergencies.

Sinabung on September 13, 2010. Note the fields and settlements extending up those slopes on the left — they only had three more years of existence left. (Image: Kendrick95 via Wikimedia, CC BY-SA 3.0)

As problems in social and governmental responses were worked out, the eruption ended in mid-September.

Everyone breathed a sigh of relief except the volcanologists, whose monitoring showed them that Sinabung had not gone completely back to sleep.

The volcano did give everybody a three-year break, though.

This allowed locals time to cope with their losses — mainly economic and property related, since casualties were few. They also had a chance to adjust to the idea of having an active volcano in the neighborhood.

Government scientists used the interval to improve monitoring capabilities at the Sinabung Volcano Observatory, while the world’s volcanologists set a number of studies in motion.

In short, when Sinabung erupted again on September 15, 2013, everyone was much better prepared.

Which was good, because this time the volcano really opened up for business, with a lava dome first seen in December 2013.

After that came a dome collapse in early 2014, followed by a thick lava flow oozing down the flank.

Then a series of dome/collapse/pyroclastic flow rounds began, starting from about mid-September 2014 onward.



Some people around Sinabung opened up for business, too. Hear all the cameras clicking in the background? Volcano tourism became a thing here in 2014, thanks to Sinabung’s amazing photo opportunities, like this series of vortices after a pyroclastic flow.


There were more fatalities during this round of activity, in 2014 and 2016: dozens of people caught by pyroclastic flows while in the exclusion zone that extends out several kilometers from the fiery summit.

Those fields and settlements seen on the left in the 2010 image earlier are now under that flow field in this front-facing shot. Evacuations got everyone out of harm’s way before it happened, but they can never go back. (Image: Akhmad Dody Firmansyah/Shutterstock)

By 2017, Sinabung had built an impressive flow and lava field.

Volcanic activity began slowing in 2017 and actually paused for nine months.

After a few explosions in May and June 2019, all was calm until one night about a week ago, when this happened:


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That was followed two days later by a larger blast (below), and as of this weekend, Sinabung is once again having almost continuous explosions.


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Ashfall turned day into night in the nearby city of Berastagi.


I haven’t heard news yet of any lava sightings, but it’s clear that Mount Sinabung will never again be ranked among “the quiet ones.”

Location:

3.17° N, 98.392° E, in Karo Regency, North Sumatra Province, Indonesia. The GVP Volcano Number is 261080.

Nearby Population:

Per the Global Volcanism Program:

  • Within 5 km (3 miles): 997
  • Within 10 km (6 miles): 13,801
  • Within 30 km (19 miles): 163,630
  • Within 100 km (62 miles): 7,646,883

Current Status:

Level III on a four-point scale since May 20, 2019. Aviation Code raised to Red on August 14, 2020.

Eruptions:

  • Eruption styles: Steam-based explosions like those seen recently, followed by lava dome construction and collapse; thick, gooey lava flows (the edges of which also may collapse); and pyroclastic flows and surges from collapses.

    The geological record shows that Sinabung did much the same thing during its last eruption before modern times, around 740-880 AD.

    And despite this volcano’s flair for drama, no evidence of Plinian-style activity in the past has yet been found here. (Photovolcanica)



    This August 10 explosion is vulcanian. Eruptions don’t have to be Plinian to be scary, dangerous, and costly (thus far, ash has caused more than two million dollars’ worth of damage to local crops).


  • Biggest recorded event: Two VEI 4 eruptions, listed as running from September 2013 through August 2018, and from approximately February 2019 to June 9, 2019. (Global Volcanism Program)

    I don’t know if this February 19, 2018, explosion was the largest blast to date, but it did blow almost 2,000,000 m3 off the summit. (Wikipedia)


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  • Most recent eruption: August 2020, ongoing.
  • Past history: Sinabung has built itself up over the last 70,000 years or so through a combination of pyroclastic flow deposits and lava flows/domes. However, the only confirmed history is what has happened over the last ten years plus similiar activity about 1,200 years ago. See the Global Volcanism Program for details. They also have a bulletin archive for major events at Sinabung from 2010 to 2019.

Monitoring:

The Indonesian Center for Volcanology and Geologic Hazard Mitigation (CVGHM); US Geological Survey/USAID Volcano Disaster Assistance Program; and Kyoto University.

Most recent updates and activity notices (both sites in Indonesian; last notice at time of writing is August 14, 2020).


Featured image: Ahmad Zikri/Shutterstock


Sources:

Some of these are in Indonesian and were translated using browser translation or Google Translate online.

Brown, S.K.; Jenkins, S.F.; Sparks, R.S.J.; Odbert, H.; and Auker, M. R. 2017. Volcanic fatalities database: analysis of volcanic threat with distance and victim classification. Journal of Applied Volcanology, 6: 15.

Chaussard, E., and Amelung, F. 2012. Precursory inflation of shallow magma reservoirs at west Sunda volcanoes detected by InSAR. Geophysical Research Letters, 39(21).

Global Volcanism Program, 2020. Report on Sinabung (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 5 August-11 August 2020. Smithsonian Institution and US Geological Survey. https://volcano.si.edu/showreport.cfm?doi=GVP.WVAR20200805-261080

Gunawan, A. 2020. Karo farmers suffer Rp 41.8 billion in losses due to Mount Sinabung eruption. https://www.thejakartapost.com/news/2020/08/14/karo-farmers-suffer-rp-41-8-billion-in-losses-due-to-mt-sinabung-eruption.html Last accessed August 15, 2020.

Gunawan, H.; Budianto, A.; Prambada, O.; McCausland, W.; and others. 2019. Overview of the eruptions of Sinabung Volcano, 2010 and 2013–present and details of the 2013 phreatomagmatic phase. Journal of Volcanology and Geothermal Research, 382: 103-119.

Hotta, K.; Iguchi, M.; Ohkura, T.; Hendrasto, M.; and others. 2019. Magma intrusion and effusion at Sinabung volcano, Indonesia, from 2013 to 2016, as revealed by continuous GPS observation. Journal of Volcanology and Geothermal Research, 382: 173-183. https://www.sciencedirect.com/science/article/pii/S0377027317307436

McCausland, W. A.; Gunawan, H.; White, R. A.; Indrastuti, N.; and others. 2019. Using a process-based model of pre-eruptive seismic patterns to forecast evolving eruptive styles at Sinabung Volcano, Indonesia. Journal of Volcanology and Geothermal Research, 382: 253-266. https://www.sciencedirect.com/science/article/pii/S0377027317302007

Mucek, A. E.; Danišík, M.; de Silva, S. L.; Schmitt, A. K.; and others. 2017. Post-supereruption recovery at Toba Caldera. Nature Communications, 8(1): 1-9. https://www.nature.com/articles/ncomms15248

Nugraha, A. D.; Indrastuti, N.; Kusnandar, R.; Gunawan, H.; and others. 2019. Joint 3-D tomographic imaging of Vp, Vs and Vp/Vs and hypocenter relocation at Sinabung volcano, Indonesia from November to December 2013. Journal of Volcanology and Geothermal Research, 382: 210-223. https://www.sciencedirect.com/science/article/pii/S0377027316303250

Photovolcanica. 2015. Sinabung Volcano (Gunung Sinabung). http://www.photovolcanica.com/VolcanoInfo/Sinabung/Sinabung.html Last accessed August 15, 2020.

Syarief, I. S. 2020. Mount Sinabung still sprays volcanic dust. https://www.suarasurabaya.net/kelanakota/2020/gunung-sinabung-masih-semburkan-debu-vulkanik/ Last accessed August 15, 2020.

Wikipedia. 2020. Mount Sinabung https://en.wikipedia.org/wiki/Mount_Sinabung Last accessed August 15, 2020.



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