Spatio-temporal characteristics of volcanic tremor at Shinmoe dake by seismic observation

2014 Fiscal Year Final Research Report

• Project/Area Number: 24540457
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Solid earth and planetary physics
• Research Institution: Kyushu University
• Principal Investigator: MATSUMOTO Satoshi 九州大学, 理学(系)研究科(研究院), 准教授 (40221593)
• Co-Investigator(Renkei-kenkyūsha): SHIMIZU Hiroshi 九州大学, 大学院理学研究院, 教授 (50178985) ; MATSUSHIMA Takeshi 九州大学, 大学院理学研究院, 准教授 (40222301)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 火山性微動 / 地震計アレイ / 新燃岳

Outline of Final Research Achievements

We investigated characteristics of the volcanic tremor occurred at Shinmoedake volcano, Japan. Detailed analysis for the seismograms obtained by two seismic arrays and stations deployed near the volcano provided the source locations and focal mechanism of the tremor. We observed changes in the seismic ray direction during a volcanic tremor sequence and inferred two major sources of the tremor from the slowness vectors of the approaching waves. One was located in a shallow region beneath the crater. The other was found in a direction N30W from the array, pointing to a location above a pressure source. The time evolution of the tremor suggests that instability occurs at the edge of the conduit. The fine volcanic tremor structure suggests an interaction between conduits located in both deep and shallow depths. Source models were also estimated from observed radiation pattern of the tremor at the seismic network. The sources were modeled by almost horizontal tesile cracks.

Free Research Field

地震学