Volcanic Gravity Flow Simulations on Volcanic Area
Our portal site, users can perform numerical simulations of volcanic gravity flows such as pyroclastic flows, pyroclastic surges and debris avalanches for prediction and mitigation of the hazard.
In the following example, we conducted an energy-cone simulation of pyroclastic flows using ASTER images of Merapi volcano taken on June 30, 2003. For areas covered by clouds and volcanic plumes, we eliminated these clouds and plumes using another scene taken on Aug. 5, 2002.
The concept of the energy cone simulation is very simple. As shown in the first figure, we calculated potential energy of pyroclastic flows. The H/L ratio (H=height, L=travel distance) is equal to the coefficient of friction of pyroclastic flows. The relationship between H/L ratio and the volume is known from the block-and-ash flows during the 1991-95 Unzen eruption (H/L=0.2-0.4). For example, the H/L ratio is ca. 0.4 for 104 m3 scale pyroclastic flows, 0.3 for 105 m3, and 0.2 for 106 m3.
- The Figure 1 is showing calculation results for Hc=0m, H/L=0.15, 0.2, 0.25, 0.3, 0.35, and 0.4. (Hc is column collapse height)
- The Figure 2 is showing calculation results for Hc=60m, H/L=0.15, 0.2, 0.25, 0.3, 0.35, and 0.4. We thought that height of the lava dome is getting higher compared from the 2003 satellite image.
- These H/L ratio lines in the map indicate possible devastation area by the pyroclastic flows from the Merapi lava dome.
Agreement
GEO Grid provides this volcanic gravity flow simulations for the purpose of volcanic disaster mitigations. The results show potential affected area caused by volcanic flows. AIST strongly recommends that consulting with specialists, in the case of using simulation results on real hazards. AIST is exempt from responsibility for compensation using this simulation results. AIST requests users to take full responsibility.