Pathways and Vents of Dyke Intrusion: Insights from Analog Experiments with Silica Powder
Yukio Fukuyasu1, Ryo Tanaka2
Affiliations: 1Graduate School of Science, Hokkaido University, Japan; 2Institute of Seismology and Volcanology, Faculty of Science, Hokkaido University, Japan
Presentation type: Poster
Presentation time: Tuesday 16:30 - 18:30, Room Poster Hall
Poster Board Number: 82
Programme No: 3.16.9
Abstract
Numerous studies using analog experiments and numerical simulations have explored the mechanisms governing magma intrusion pathways and vent locations, emphasizing the role of edifice loading. Previous powder experiments simulating high-viscosity magma intrusion showed that magma avoids volcanic edifices; however, no study has investigated intrusion from various horizontal positions relative to an edifice. Mt. Usu, an active volcano in southwestern Hokkaido, has a truncated cone shape (ca. 500 m height, with an upper radius of 0.6 km and a basal radius of 3 km). Its eruptions occur at diverse vent locations, including the summit and flanks, with varying eruption styles by site. Even within the summit crater, vent locations show variability. To study the impact of horizontal intrusion positions on magma pathways, we conducted two-dimensional analog experiments using silica powder as the host rock and syrup to simulate high-viscosity magma. A trapezoidal structure mimicking Mt. Usu was placed on the apparatus with intrusion points set beneath the center, edge, and middle of the trapezoid's upper surface. Results showed that magma intruded beneath the center followed a curved path to the upper surface. Magma intruded beneath the middle and edge bifurcated, erupting from both the slope and base. These findings suggest that horizontal positional relationships between the volcanic edifice and intrusion points strongly influence diverse vent locations on Mt. Usu's summit and flanks, while the summit crater exhibits less variation in eruption sites.