Initiation and eruption style of silicic volcanism: Roles of outgassing and rheology of crystal- and bubble-bearing magmas

2017 Fiscal Year Final Research Report

• Project/Area Number: 15H03714
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Solid earth and planetary physics
• Research Institution: Tohoku University
• Principal Investigator: Okumura Satoshi 東北大学, 理学研究科, 准教授 (40532213)
• Co-Investigator(Kenkyū-buntansha): 小園 誠史 東北大学, 理学研究科, 准教授 (40506747) ; 栗谷 豪 北海道大学, 理学研究院, 准教授 (80397900)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 高結晶度マグマ / 爆発的噴火 / マグマレオロジー / 脱ガス / 発泡

Outline of Final Research Achievements

Crystal-rich magmas with high viscosity often cause explosive volcanism. To ascend rapidly to the surface, the magma must be lubricated during the eruption. We performed decompression experiments for bubble- and crystal-bearing magmas to simulate magma ascent process. We also measured the viscosity of magmas with gas bubbles and crystals. Based on these experiments, we found that crystal-rich magma can lubricate due to the breakage of crystal network with gas bubble formation under high decompression rates. In contrast, gas bubbles escaped under low decompression rates. Thus, we infer that explosive volcanism by crystal-rich magmas can cause when high decompression rate is achieved by some mechanisms such as large overpressure in a magma reservoir.

Free Research Field

火山学