Decoding seismic and infrasonic waves associated with Plinian-type eruptions for understanding magma fragmentation and transition of the eruptive activity.

2014 Fiscal Year Final Research Report

• Project/Area Number: 24340101
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Solid earth and planetary physics
• Research Institution: The University of Tokyo
• Principal Investigator: ICHIHARA Mie 東京大学, 地震研究所, 准教授 (00376625)
• Co-Investigator(Renkei-kenkyūsha): SUZUKI Yuki 早稲田大学, 教育・総合科学学術院, 専任講師 (00374918) ; YOKOO Akihiko 京都大学, 理学系研究科, 助教 (70420403)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 火山現象 / 噴火 / 地震 / 空振

Outline of Final Research Achievements

A Plinian eruption emits a large amount of magma fragments into the atmosphere for a long duration and is the most energetic and hazardous type of a volcanic eruption. This study aims at clarifying the mechanism of start-up and transition of such an eruption. The three sub-Plinian eruptions during the Shinmoe-dake 2011 eruption were chosen as the test case, because multi-disciplinary high-quality data are available. We performed combined analyses of seismic and infrasonic signals and compared the results with the material study for the eruption products, image analyses, and model experiments in the laboratory. It is confirmed that the first and the third sub-Plinian eruptions were triggered by rapid decompression due to shallow process, while the second event grew internally driven by highly vesicular magma from below.

Free Research Field

火山物理学