Why do volcanoes collapse? Analysis of matrix facies of debris avalanche deposits and prediction of future collapses

火山为什么会塌陷？

• 批准号: 22H01306
• 负责人: 片岡 香子
• 金额: $ 11.65万
• 依托单位: Niigata University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2022
• 资助国家: 日本
• 起止时间: 2022-04-01 至 2025-03-31
• 项目状态: 未结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-22H01306/
• 关键词: 山体崩壊; 岩屑なだれ; ラハール; 熱水変質; 磐梯山

本研究は，過去に繰り返し火山体崩壊を起こした福島県磐梯山に注目し，岩屑なだれ堆積物とラハール堆積物の基質部を多面的に分析し，山体崩壊時の山体内部の変質環境を再構築することから，崩壊の要因である山体内部の脆弱性の特徴を明らかにすることを目的とする。今年度は，対象地域となる磐梯山周辺で野外地質調査を行い，過去約5万年間の岩屑なだれ堆積物（翁島岩屑なだれ・磐根岩屑なだれ・古観音岩屑なだれ・滝ノ沢岩屑なだれ・小水沢岩屑なだれ・琵琶沢岩屑なだれ・1888年岩屑なだれ）とそれに連鎖して発生したラハール堆積物の記載と基質部の採取を重点的に行った。また，猪苗代湖で2021年に採取された7ｍ長のピストンコア堆積物は過去約4000年間のイベントを記録しており，そこには岩屑なだれ堆積物の遠方層が複数挟まることから，層序と対比からその堆積年代もあわせて検討し，その成果の一部は国際火山学会で発表した。岩屑なだれ堆積物とラハール堆積物の一部は，篩いとレーザー回折式粒度分析計を用いて，粒度分析を行った。また基質部から火山ガラスの検出を試みた。さらに，蛍光X線分析（XRF）によって明らかとなった基質部に含まれる硫黄含有量をもとに，高い硫黄含有量を持つ安達太良山や御嶽山のラハール堆積物を比較試料として，質量分析計を用いた硫黄安定同位体分析の予備実験を行った。これにより，岩屑なだれ堆積物やラハール堆積物の基質部からの硫黄の抽出と同位体分析が可能となった。堆積物基質部の粘土鉱物・変質鉱物を解析するにあたり，卓上型X線回折装置（XRD）を新規に導入し，周辺機器を含め，分析環境を整えた。

In this study, in the past, when the volcanic body collapsed, there was a lot of attention in the mountain, and there was a multi-faceted analysis of the active material in the cuttings pile, the active material in the mountain, the environmental environment in the mountain during the collapse, and the collapse because of the vulnerability in the mountain. In this year's festival, it looks like an area, a mountain, a mountain, a field trip. Over the past 50, 000 years or so, the active materials of cuttings in the past 50, 000 years (Wengfu cuttings, cuttings, cuttings, In 2021, Pig Miaodai Lake collected the raw materials of the 7m-long thermal cycle reactor in the past 4000 years, and the clippings were collected in the past 4000 years. The positive materials of the cuttings pile were collected in the past 4000 years, and the sequence was compared to that of the international society of volcanoes. The cuttings are divided into two parts: the cuttings, the active materials, the active materials, the cuttings, the active materials, the active materials, the cuttings, the active materials, the active materials, the cuttings, the active materials, the active materials, the cuttings, the active materials, the active materials, the cuttings, the cuttings, the active materials, the active materials, the cuttings, the active materials, the active materials, the cuttings, the cuttings In the base department, the volcano will make an attempt to make an attempt. X-ray analysis (XRF) shows that the content of sulfur in the base part is sensitive to the content of sulfur, while the content of sulfur is higher than that of the raw material in Mount Anda Tailiang Mountain, and the quantitative analysis program is used to analyze the sulfur content of the equipment. The cuttings and cuttings may be extracted from the base of the active material of the pile, and the sulfur may be extracted by isotope analysis. In the base part of the reactor, the clay material is analyzed, the new specification of the top X-ray folding device (XRD) is introduced, the perimeter machine is included, and the environment is analyzed.

项目成果

Sulfide mineralogy and whole-rock sulfur isotope composition of high-grade metamorphic rocks from the Sor Rondane Mountains, East Antarctica.

东南极洲索尔龙丹山脉高级变质岩的硫化物矿物学和全岩硫同位素组成。

• 发表时间: 2022
• 作者: Kawakami;T.;Satish-Kumar;M.;Mitsubori;T.;Silpa A. S.
• 通讯作者: Silpa A. S.