Journal cover Journal topic
Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/nhess-2018-120
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
07 May 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Natural Hazards and Earth System Sciences (NHESS).
Dome instability at Merapi volcano identified by drone photogrammetry and numerical modeling
Herlan Darmawan1,2, Thomas R. Walter1, Valentin R. Troll3,4, and Agus Budi-Santoso5 1Dept. Physics of Earth, GFZ German Research Center for Geosciences, Telegrafenberg, 14473, Potsdam, Germany
2Laboratory Laboratory of Geophysics, Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Yogyakarta, Indonesia
3Dept. of Earth Science, Section for Mineralogy, Petrology and Tectonics, Uppsala University, Villavägen 16, SE-752 36 Uppsala, Sweden
4Faculty of Geological Engineering, Universitas Padjajaran, Jatinangor 45363, Bandung, Indonesia
5BPPTKG (Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi), Jalan Cendana 15, Yogyakarta 55166, Indonesia
Abstract. The growth of lava domes may cause gradual oversteepening and can lead to gravitational instability and eventual collapse to produce pyroclastic flows that may travel up to several kilometers from a volcano’s summit. At Merapi volcano, Indonesia, pyroclastic flows are a major hazard, frequently involving high numbers of casualties. After the VEI 4 eruption in 2010, a new lava dome developed on Merapi volcano and was structurally destabilized by six steam-driven explosions between 2012 and 2014. Previous studies revealed that the explosions produced elongated open fissures and a structurally delineated sector at the southern part of the dome complex. Here, we investigate the geometry, thermal fingerprint, and hazard potential of the delineated unstable dome sector by integrating drone-based geomorphologic data and forward-looking thermal infrared images. The sector located on the un-buttressed southern flank of the steep dome that is delineated by a horseshoe-shaped structure and we identify intense thermal and fumarolic activity along this structure, hosting the high temperatures of the current dome. From the morphology, structures, and thermal mapping, we conjecture that the horseshoe shaped structure may develop into a failure plane that could lead to gravitational collapse of the unstable dome sector. To further elaborate on this instability hypothesis, we calculate the factor of safety, and run a numerical model of the resulting block and ash flows depositional area using Titan2D. Results of factor of the safety analysis confirm dome instability, especially during typical rainfall events. The titan2D model suggests that a hypothetical gravitational collapse of the delineated unstable dome sector would travel southward for up to 4 km distance. This study highlights the relevance of structural development of lava domes, which can affect hazards even years after dome emplacement, and influences the development of thermal and fumarolic activity of cooling lava domes.
Citation: Darmawan, H., Walter, T. R., Troll, V. R., and Budi-Santoso, A.: Dome instability at Merapi volcano identified by drone photogrammetry and numerical modeling, Nat. Hazards Earth Syst. Sci. Discuss., https://doi.org/10.5194/nhess-2018-120, in review, 2018.
Herlan Darmawan et al.
Herlan Darmawan et al.

Data sets

High resolution Digital Elevation Model of Merapi summit in 2015 generated by UAVs and TLS H. Darmawan, T. R. Walter, N. Richter, and M. Nikkhoo, https://doi.org/10.5880/GFZ.2.1.2017.003
Herlan Darmawan et al.

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Short summary
In Merapi volcano, lava dome failure may generate pyroclastic flow and threaten populations who living on its flanks. Here, I assessed the potential hazard of the Merapi lava dome by using drone photogammetry and numerical modeling. Results show a weak structural depression that associated with high thermal at the southern Merapi lava dome sector. The southern lava dome sector may further destabilize by a typical rainfall at Merapi summit and produce pyroclastic flow up to 4 kilometers distance.
In Merapi volcano, lava dome failure may generate pyroclastic flow and threaten populations who...
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