2024-02-01 ペンシルベニア州立大学(PennState)
◆アラスカと日本の岩石層の手がかりから、科学者たちは沈み込み帯での圧力溶解活動を予測する新しいモデルを開発しました。岩石が強い圧力のもとで一緒に押し潰されると、圧力溶解が形成され、岩石が変形し、地質プレートが互いに滑り過ぎる方法に影響を与えます。
◆このプロセスは地震発生前において重要であり、研究者はこれを理解することで地震の発生地点を特定する手がかりを得ることができます。
＜関連情報＞
- https://www.psu.edu/news/research/story/ancient-rocks-improve-understanding-tectonic-activity-between-earthquakes/
- https://www.science.org/doi/10.1126/sciadv.adi7279
地震発生帯の圧力解流則： カスケーディアへの適用 A pressure solution flow law for the seismogenic zone: Application to Cascadia
DONALD M. FISHER AND GREG HIRTH
Science Advances Published:24 Jan 2024
DOI:https://doi.org/10.1126/sciadv.adi7279
Abstract
We develop a linear viscous constitutive relationship for pressure solution constrained by models of deformed metasedimentary rocks and observations of exposed rocks from ancient subduction zones. We include pressure and temperature dependence on the solubility of silica in fluid by parameterizing a practical van’t Hoff relationship. This general flow law is well suited for making predictions about interseismic behavior of subduction zones. We apply the flow law to Cascadia, where thermal structure, geometry, relative plate velocity, and Global Positioning System velocity field are well constrained. Results are consistent with the temperature conditions at which resolvable ductile strain is recorded in subducted mudstones (at depths near the updip limit of the seismogenic zone) and with relative plate motion accommodated completely by viscous deformation (at depths near the downdip limit of the seismogenic zone). The flow law also predicts the observed forearc tapering of slip rate deficit with depth.
