シリカ濃縮による潜水地帯の緩やかな地震周期性の制御の可能性
Pascal Audet1, Roland Bürgmann2
1Department of Earth Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
Nature
|June 20, 2014
まとめ
サブドクションゾーンのゆっくりとした地震は,シリカが豊富な前弓の地殻と関連しています. 地震波の速度によって示されるシリカの含有量の増加は,スロースリップイベントと震動の再発時間の短縮と相関しています.
科学分野:
- 地質物理学 地質物理学とは地質物理学です.
- 地震学 地震学とは
- テクトニクス (地質学) とは
背景:
- ゆっくりとした地震は,エピソード的な震動と滑り込みを含む,数ヶ月から数年の間隔で再発するサブダクションゾーンの前弓で発生します.
- これらのイベントには高孔液圧が必要ですが,再発時間変動を制御する要因は不明です.
- カスカディアでは,スロースリップセグメンテーションと震動の特徴は深さによって変化し,局所的な制御を示唆しています.
研究 の 目的:
- フロアークの地殻特性と地震の再発時間が遅いとの関係を調査する.
- サブダクションゾーンにおける遅い地震の振る舞いの変動を制御する物理的メカニズムを特定する.
- 地震活動の調節におけるシリカ濃縮と流体圧の役割を調査する.
主な方法:
- サブドクションゾーンの前弓からの地震データ (圧縮波とスイール波の速度) の収集と分析.
- 地震速度比 (vP/vS) と,ゆっくりとした地震再発間隔の相関.
- 地質学的および地物理学的観測を,流体岩相互作用の理論的モデルと統合する.
主要な成果:
- 前弓地殻の平均圧縮 (P) 波と切断 (S) 波の速度比 (vP/vS) と遅い地震再発時間との間には,線形的な関係がある.
- Forearc vP/vS値は1.6から2.0の範囲で,シリカ濃縮量 (体積5~15%) と相関しています.
- 北のカスカディアでは,深さと共にvP/vSが減少すると,震の再発間隔が短くなる.
結論:
- スラブから派生した流体からの前弓の地殻のシリカ濃縮はvP/vS値を制御し,遅い地震行動に影響を与えます.
- 温度に依存するシリカ堆積と断層の溶解-沈殿のクリープは,流体の過圧の蓄積と再発時間の短縮につながり,透過性を低下させます.
- これらのプロセスは,膨張力の強化と組み合わせて,ゆっくりとした地震の再発と震動活動の観察された変動性を支配します.
さらに関連する動画
11:50Metal-silicate Partitioning at High Pressure and Temperature: Experimental Methods and a Protocol to Suppress Highly Siderophile Element Inclusions
Published on: June 13, 2015
12.0K
06:04Simulation of the Planetary Interior Differentiation Processes in the Laboratory
Published on: November 15, 2013
11.3K
関連する概念動画
Feedback Regulation of Calcium Concentration
2.9K
Calcium is an essential signaling molecule required for various cellular functions. Calcium pumps and ion channels on cell and organellar membranes, such as those on the endoplasmic reticulum (ER), regulate calcium concentrations inside the cell. They remain closed, keeping the cytosolic calcium levels low at a resting state.
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
2.9K
Deep Sea Microbial Ecology
53
The deep ocean and its underlying sediments represent vast, largely unexplored microbial habitats that extend far beyond the sunlit photic zone. The photic (euphotic) zone typically spans the upper ~100–200 meters of pelagic waters in the open ocean, but its depth varies geographically and seasonally, where sufficient light supports photosynthetic life. Below this lies the deep sea, spanning roughly 1000–6000 meters (bathypelagic to abyssal zones), with deeper hadal trenches...
53
Minerals
1.7K
Minerals are essential nutrients that the human body needs in small amounts to work properly. They play a vital role in many bodily functions, such as building strong bones and transmitting nerve impulses. Some minerals are needed for hormone production or to maintain a normal heartbeat. Major minerals include calcium, phosphorus, potassium, sulfur, sodium, chlorine, and magnesium, while trace minerals include iron, manganese, copper, iodine, zinc, cobalt, fluoride, and selenium.
Major...
Major...
1.7K
Magnetic Susceptibility and Permeability
2.9K
In linear magnetic materials, like paramagnets and diamagnets, magnetization is proportional to the magnetic field intensity. The constant of proportionality, a dimensionless number, is called magnetic susceptibility. The value of the susceptibility depends on the type of material.
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...
2.9K
Effect of Sea Water on Concrete
1.4K
Concrete exposed to seawater can undergo degradation like the dissolution of ettringite and gypsum, increasing the material's porosity and decreasing its strength. In contrast, the crystallization of salts within the concrete's pores can cause expansion, particularly above the waterline where evaporation occurs. Nonetheless, this expansion only happens when seawater, enabled by the concrete's permeability, manages to infiltrate the structure.
Concrete in areas between tide marks,...
Concrete in areas between tide marks,...
1.4K
