Merapi has become one of the most enticing volcanoes due to its activity over the past century. Although we have to agree that the 2010 VEI = 4 (Volcanic Explosivity Index, [1]) eruption is the greatest in its recorded history, Merapi is more famous for its shorter cycle of smaller scale, making it one of the most active volcanoes on Earth. Many mechanisms are involved in an eruption, and pyroclastic flow is the most dangerous occurrence in terms of volcanic hazard. A pyroclastic flow is defined as a high-speed avalanche consisted of high temperature mixture of rock fragments and gas, resulted from lava dome collapse and/or gravitational column collapse. Researchers have studied Merapi’s history and behavior, and numerical simulations are an important tool for future hazard mitigation. By utilizing numerical simulation on basal part of pyroclastic flow, we investigated the applicability of the simulation on pyroclastic flows from historical eruptions of Merapi (1994, 2001, and 2006). Herein, we present a total of 32 simulations and discuss the areas affected by pyroclastic flows and the factors that affect the simulation results.

1. [1] C. G. Newhall and S. Self, “The volcanic explosivity index (VEI) an estimate of explosive magnitude for historical volcanism,” J. Geophys. Res., Vol.87, C2, pp. 1231-1238, 1982.
2. [2] B. Voight, K. Young, D. Hidayat, Subandrio, M. Purbawinata, A. Ratdomopurbo, Suharna, Panut, D. Sayudi, R. LaHusen, J. Marso, T. Murray, M. Dejean, M. Iguchi, and K. Ishihara, “Deformation and seismic precursors to dome-collapse and fountain-collapse nuées ardentes at Merapi Volcano, Java, Indonesia,” J. of Volcanology and Geothermal Research, Vol.100, pp. 261-287, 2000.
3. [3] Balai Penyelidikan dan Pengembangan Teknologi Kegunungapian (BPPTKG), “Precursor Erupsi Gunung Merapi,” Yogyakarta: Pusat Vulkanologi dan Mitigasi Bencana Geologi, Badan Geologi, Departemen Energi dan Sumber Daya Mineral, 2006 (in Indonesian).
4. [4] H. Itoh, J. Takahama, M. Takahashi, and K. Miyamoto, “Hazard estimation of the possible pyroclastic flow disasters using numerical simulation related to the 1994 activity at Merapi Volcano,” J. of Volcanology and Geothermal Research, Vol.100, pp. 503-516, 2000.
5. [5] S. Yamashita and K. Miyamoto, “Model of pyroclastic flow and its numerical simulation,” Sediment Problems: Strategies for Monitoring, Predictions and Control, Proc. of the Yokoyama Symp., Vol.IAHS Publ., No.217, 1993.
6. [6] K. Miyamoto, Y. Gonda, S. Yamashita, and H. Matsuyoshi, “EGU Presentation,” 2011, https://presentations.copernicus.org/EGU2011-12984_presentation.pdf [accessed July 29, 2018]
7. [7] A. Ratdomopurbo, F. Beauducel, J. Subandriyo, I. Agung Nandaka, C. Newhall, J. Suharna, D. Sayudi, H. Suparwaka, and S. Sunarta, “Overview of the 2006 eruption of Mt. Merapi,” J. of Volcanology and Geothermal Research, Vol.261, pp. 87-97, 2013.
8. [8] C. Gerstenecker, G. Läufer, B. Snitil, and B. Wrobel, “Digital Elevation Models for Mount Merapi, Decade-Volcanoes Under Investigation,” Merapi-Galeras Workshop, Postdam, pp. 65-68, 1998.
9. [9] T. Yamamoto, S. Takarada, and S. Suto, “Pyroclastic flows from the 1991 eruption of Unzen volcano, Japan,” Bull Volcano., Vol.55, pp. 166-175, 1993.
10. [10] A. B. Clarke, B. Voight, A. Neri, and G. Macedonio, “Transient dynamics of vulcanian explosions and column collapse,” Nature, Vol.415, pp. 897-901, 2002.