Seismogenic, electrically conductive, and fluid zones at continental plate boundaries in New Zealand, Himalaya, and California

摘要: We explore the idea that fluid occurrence below seismogenic zone plays an active role in rupture process by examining how fluids spatially relate to seismicity at three continental plate boundaries: South Island of New Zealand, Himalaya, and San Andreas fault, USA. With this objective, we project earthquake hypocenters onto magnetotelluric (MT) electrical resistivity cross-sections. MT detection conductive zones crust containing low fractions (<1%) requires interconnected network fluid-filled porosity facilitated shearing, fracturing, and/or grain-edge wetting. Mechanisms promoting reservoirs ductile include: �) stalling upward propagating waves, 2) tectonically induced neutral buoyancy, 3) development shear zones. Distinct horizons are detected depth Zealand Himalaya where tectonic convergence is high. In Parkfield segment low, there high conductivity but it forms a sub-vertical corridor surface with no distinct top. The tops sub-horizontal ~20 km ~25–40 extends only �2 25 depth, respectively. deep layer may have originated as “water sill” facilitating water-weakening, localized deformation, eventually becoming water-rich, anisotropic, mylonized, zone. Fluid exchange through Alpine fault initiate or be initiated rupture. Localized, unstable flow fluidized trigger earthquakes above.