シリカ鉱物析出による地殻の透水-不透水境界の地球化学的発展

Tohoku University土屋範芳課

An Explanation of Episodic Tremor and Slow Slip Constrained by Crack-Seal Veins and Viscous Shear in Subduction Mélange

Episodic tremor and slow slip (ETS) occurs in the transition zone between the locked seismogenic zone and the deeper, stably sliding zone. Actual mechanisms of ETS are enigmatic, caused by lack of geological observations and limited spatial resolution of geophysical information from the ETS source. We report that quartz‐filled, crack‐seal shear and extension veins in subduction mélange record repeated low‐angle thrust‐sense frictional sliding and tensile fracturing at near‐lithostatic fluid pressures. Crack‐seal veins were coeval with viscous shear zones that accommodated deformation by pressure solution creep. The minimum time interval between thrusting events, determined from a kinetic model of quartz precipitation in shear veins, was less than a few years. This short recurrence time of low‐angle brittle thrusting at near‐lithostatic fluid overpressures within viscous shear zones may be explained by frequent release of accumulated strain by ETS

An explanation of episodic tremor and slow slip constrained by crack-seal veins and viscous shear in subduction mélange

Episodic tremor and slow slip (ETS) occurs in the transition zone between the locked seismogenic zone and the deeper, stably sliding zone. Actual mechanisms of ETS are enigmatic, caused by lack of geological observations and limited spatial resolution of geophysical information from the ETS source. We report that quartz‐filled, crack‐seal shear and extension veins in subduction mélange record repeated low‐angle thrust‐sense frictional sliding and tensile fracturing at near‐lithostatic fluid pressures. Crack‐seal veins were coeval with viscous shear zones that accommodated deformation by pressure solution creep. The minimum time interval between thrusting events, determined from a kinetic model of quartz precipitation in shear veins, was less than a few years. This short recurrence time of low‐angle brittle thrusting at near‐lithostatic fluid overpressures within viscous shear zones may be explained by frequent release of accumulated strain by ETS

Nイロ キ ノ ケイスウ ニツイテ

First, it is introduced that the number of labeled n-colored trees (Tα_1α_2・・・α_n) with n distinctly-colored point-subsets is determined by　　　Tα_1α_2・・・α_n = α^II^^n__(α-α_i)^　where α=∑^^n__(i=1)α_i. Next, several theorems and lemmata on these trees are proved and lastly their practical examples for electrical networks are described.　　異った色に塗られたＮ組の点集合（同集合同色）について，異色の点対にのみ枝を張ることを許したグラフをＮ色グラフという。Ｎ色グラフが木ならＮ色木といい，それぞれα_1α_2・・・α_n個の点が同色ならＴα_1α_2・・・α_nと書く。本文ではＴα_1α_2・・・α_nの種類を数える一般公式　　　Ｎ（Ｔα_1α_2・・・α_n）＝α^Ⅱ^^n__（α－α_i）^　と，これらに関するいくつかの公式を示し，その電気回路への二三の応用例を掲げる。しかも，これらの公式は一般のグラフＧ_nに関する公式を含んでいることを示した