長期の地震と共同噴出ドームの膨張は,粒子画像速度測定で観測されています
Jeffrey B Johnson1, Jonathan M Lees, Alexander Gerst
1Department of Earth and Environmental Science, New Mexico Tech, Socorro, New Mexico 87801, USA. jeff.johnson@ees.nmt.edu
Nature
|November 21, 2008
まとめ
研究者らは,光学ジオデシーと地震データを組み合わせて,グアテマラのサンティアギトー火山での火山地震を研究した. 彼らは,質量移転によって引き起こされる突然のドーム変形が,これらの地震現象を生成し,火山のプロセスに関する新しい洞察を提供することを発見しました.
科学分野:
- 地質物理学 地質物理学とは地質物理学です.
- 火山学 火山学とは
- 地震学 地震学とは
背景:
- 大陸の弧火山は,ドームの成長と爆発的な脱ガス,地震エネルギーを生成するプロセスを含む.
- 火山による地震は地質学的研究に不可欠ですが,地震の逆転はしばしばマグマ源の性質の解明に欠けています.
- 長期にわたる火山による地震はほとんど解明されていないが,世界中で観測されている.
研究 の 目的:
- 長期の火山地震の発生源を,地質観測と地震観測を組み合わせて,しっかりと制限する.
- 爆発的な噴火中のドーム変形と地震信号の関係を調べる.
- シリシウム火山系における長期地震を生成するメカニズムを理解する.
主な方法:
- 光学地質測定 (高解像度光学画像処理) とブロードバンド地震データとの組み合わせ.
- サンティアギト火山で頻繁に発生する爆発的な噴火時の地震信号とドーム変形パターンを分析した.
- 定量化されたドームの移動,伝播速度,および誘発力.
主要な成果:
- ドームの急激な垂直の表面の移転が観察され,上昇は20〜50cmで, ~50m/sで拡散しました.
- ドーム変形の加速が,記録された長期地震源と地震信号の周波数内容と関連している.
- 偶発的なドームシフトによる10^9Nを超えるピーク力を記録している.
結論:
- 凝固したドーム,導管マグマ,またはマグマパッドの急激な質量移転は,長期地震を生成するメカニズムである可能性が高い.
- 光学ジオデシーと地震データは,火山の地震源に対する強力な制約を提供します.
- この研究は,長期の火山地震とそのドーム動力学的関連性についての理解を深めます.
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