2021 Fiscal Year Final Research Report
Expansion of slow slip microearthquake into the field of subsurface fluid energy utilization
| Project/Area Number |
19K22149
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| Research Category |
Grant-in-Aid for Challenging Research (Exploratory)
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| Allocation Type | Multi-year Fund |
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| Review Section |
Medium-sized Section 31:Nuclear engineering, earth resources engineering, energy engineering, and related fields
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| Research Institution | Tohoku University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
椋平 祐輔 東北大学, 流体科学研究所, 助教 (60723799)
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| Project Period (FY) |
2019-06-28 – 2022-03-31
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| Keywords | スロースリップ地震 / ゆっくり滑り |
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| Outline of Final Research Achievements |
The seismic events, which were considered to be slow events, were detected by analyzing continuous waveform data measured in the Groningen gas field. Despite the depth of the earthquake source is thought to be around 3km-5km, events with a time duration around 30 seconds were included. When the source depth is about 3 km, the shear slip of the crack is generally several ms and the time duration of detected waveforms is several seconds general. Therefore, the event detected in this analysis seemed that the shear slip was more slowly than the normal AE. On the other hand, since the velocity structure of the field is composed of relatively low-velocity layers, it was found that detailed examination is required in consideration of such as the Q value.
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| Free Research Field |
地下計測工学
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| Academic Significance and Societal Importance of the Research Achievements |
本研究は，地下流体エネルギー開発の分野で未知の現象とされてきた低周波地震の物理現象に正面から取り組む挑戦的な研究である。低周波イベントには明瞭なP波S波も存在せず，一般的な地震学の手法でその発生位置を探ることさえ難しい。低周波イベントの理解は，貯留層のより深い理解のみならず，新たな貯留層モニタリングの手法を確立することを意味する。従来は本分野の貯留層モニタリングは微小地震計測に頼ることが多かったが低周波イベントが，スロー地震と同様に大規模な地震の前駆現象であった場合は，本分野で問題となっている誘発地震の発生リスクの評価や予測等に用いることができる。
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