Hazard estimation of the possible pyroclastic flow disasters using numerical simulation related to the 1994 activity at Merapi Volcano

A pyroclastic flow, generated at Merapi Volcano on 22 November 1994, flowed down the Boyong and Krasak Rivers, which are located on the south slope of the volcano. The flow greatly damaged the Kaliurang and Turgo areas. Following this event, it was feared that another pyroclastic flow might cause additional damage to these areas because the lava dome continued to grow increasingly unstable. There was also fear that other pyroclastic flows would affect other areas on the flanks of Merapi Volcano. Using a 2-dimensional numerical simulation, the authors estimated the areas potentially affected by further pyroclastic flow activity. Numerical simulation has proved useful in determining potential areas of inundation on the south flank of Merapi Volcano. Although the simulations are sensitive to many input parameters, we have determined that the strongest influence comes from initial flow direction and topography.