09:15 〜 09:30
[SVC31-08] 粘塑性モデルによる固結した玄武岩質溶岩流の形状の物理的解釈
Assessing the hazards of basaltic volcanoes necessitates predictions of lava flow extents based on observable quantities such as erupted volume and effusion rate. Malin (1980) empirically discovered an insightful relationship for solidified basaltic lava, demonstrating that the runout length (L) is proportional to the square root of the lava volume (V). Unfortunately, the physical mechanism underlying this empirical power-law remains misunderstood.
This study conducts morphological analyses of natural solidified lavas using the viscoplastic theory proposed by Maruishi et al. (2023, Volcanological Society of Japan), aiming to uncover the physical principles underpinning the relationship between lava dimensions, specifically the L ∝ V0.5 power-law, in terms of lava rheology and landscape features. We compiled data on the characteristic lengths of solidified lavas from geological research on Etna, Kilauea, and Mauna Loa, focusing on non-compound flows to accurately define length (L), width (W), and thickness (H). Our findings provide a method to estimate the yield stress at which lava stops, based on observed values of L, W, H, and V. The yield stress when lava stops is estimated to be 8 × 103 to 2 × 105 Pa, corresponding to the temperature at which lava stops, which is 930—1050°C.
This study conducts morphological analyses of natural solidified lavas using the viscoplastic theory proposed by Maruishi et al. (2023, Volcanological Society of Japan), aiming to uncover the physical principles underpinning the relationship between lava dimensions, specifically the L ∝ V0.5 power-law, in terms of lava rheology and landscape features. We compiled data on the characteristic lengths of solidified lavas from geological research on Etna, Kilauea, and Mauna Loa, focusing on non-compound flows to accurately define length (L), width (W), and thickness (H). Our findings provide a method to estimate the yield stress at which lava stops, based on observed values of L, W, H, and V. The yield stress when lava stops is estimated to be 8 × 103 to 2 × 105 Pa, corresponding to the temperature at which lava stops, which is 930—1050°C.