数値計算による 1986 年伊豆大島溶岩流の再現

概要

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The 1986 lava flows extruded by the fissure eruption at Izu-Oshima were reproduced by a modified method of a numerical simulation. Lava flows are regarded as Bingham fluid in the calculation. The procedure of calculations includes successive increase in viscosity and yield strength due to cooling by radiation. Two initial values of temperatures of lava are assumed, 1100℃ (5×10^4 poise) and 1000℃ (3×10^6 poise). The lava flow LCI on the western flank is reproduced better in the case that the initial temperature is 1100℃. The lava flow LB III in the caldera is reproduced better in the case that the initial temperature is 1000℃. The results suggest that the temperature at the start of the flow LB III was lower by 100℃ than that of LCI. The calculated distribution of the lava flow LB I in the caldera did not coincide with the actual one because of the insufficient precision of the topographic map and the change of topography caused by the tephra or the upheaval near the craters immediately before the extrusion of the lava.
特定非営利活動法人日本火山学会の論文
1988-06-30