A combination of geological evidence (in the form of hydrothermal vein systems in exhumed fault systems) and geophysical information around active faults supports the localized invasion of near-lithostatically overpressured aqueous fluids into lower portions of the crustal seismogenic zone which commonly extends to depths between 10 and 20 km. This is especially the case for compressional–transpressional tectonic regimes which, beside leading to crustal thickening and dewatering through prograde metamorphism, are also better at containing overpressure and are ‘load-strengthening’ (mean stress rising with increasing shear stress), the most extreme examples being associated with areas undergoing active compressional inversion where existing faults are poorly oriented for reactivation. In these circumstances, ‘fault-valve’ action from ascending overpressured fluids is likely to be widespread with fault failure dual - driven by a combination of rising fluid pressure in the lower seismogenic zone lowering fault frictional strength, as well as rising shear stress. Localized fluid overpressuring nucleates ruptures at particular sites, but ruptures on large existing faults may extend well beyond the regions of intense overpressure. Postfailure, enhanced fracture along fault rupture zones promotes fluid discharge through the aftershock period, increasing fault frictional strength before hydrothermal sealing occurs and overpressures begin to reaccumulate. The association of rupture nucleation sites with local concentrations of fluid overpressure is consistent with selective invasion of overpressured fluid into the roots of major fault zones and with observed non-uniform spacing of major hydrothermal vein systems along exhumed brittle–ductile shear zones. A range of seismological observations in compressional–transpressional settings are compatible with this hypothesis. There is a tendency for large crustal earthquakes to be associated with extensive ( L ~ 100–200 km) low-velocity zones in the lower seismogenic crust, with more local Vp/Vs anomalies ( L ~ 10–30 km) associated with rupture nucleation sites. In some instances, these low-velocity zones also exhibit high electrical conductivity. Systematic, rigorous evaluation is needed to test how widespread these associations are in different tectonic settings, and to see whether they exhibit time-dependent behaviour before and after major earthquake ruptures.

中文翻译：

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由断层阀作用引起的大地壳地震的准备带

地质证据（以挖掘断层系统中的热液脉系统的形式）和活动断层周围的地球物理信息相结合，支持近岩石静压的含水流体局部侵入地壳地震带的下部，通常延伸到 10和 20 公里。对于挤压-挤压构造体制来说尤其如此，除了通过前进变质作用导致地壳增厚和脱水之外，还可以更好地控制超压和“负载强化”（平均应力随着剪切应力的增加而增加），这是最极端的例子与正在经历活动的压缩反演的地区有关，这些地区现有的断层很难重新激活。在这些情况下，来自上升的超压流体的“断层阀”作用很可能随着断层破坏的双重作用而普遍存在 - 由低地震带中流体压力上升降低断层摩擦强度以及剪切应力上升共同驱动。局部流体超压使特定位置的破裂成核，但现有大断层上的破裂可能远远超出强烈超压区域。破坏后，沿断层破裂带的增强裂缝促进了余震期间的流体排放，在热液密封发生和超压开始重新积累之前增加了断层摩擦强度。破裂成核位置与局部流体超压浓度的关联与超压流体选择性侵入主要断层带的根部以及沿开采的脆性-韧性剪切带观察到的主要热液脉系统的非均匀间距一致。一系列挤压-挤压环境中的地震学观察结果与这一假设相一致。地壳大地震有与下发震地壳广泛（L～100～200km）低速带相关的趋势，局部Vp/Vs异常（L～10～30km）与破裂成核相关网站。在某些情况下，这些低速区域也表现出高导电性。系统的，