论文标题
地震序列和无性滑动的模拟中的断层阀和孔隙压力演变
Fault Valving and Pore Pressure Evolution in Simulations of Earthquake Sequences and Aseismic Slip
论文作者
论文摘要
断层区流体控制有效的正常应力和断层强度。尽管大多数地震模型都采用固定的孔隙流体压力分布，但地质学家已经记录了断层阀行为，即，压力的循环变化和沿断层的不稳定流体迁移。在这里，我们通过速率和状态摩擦，沿渗透性断层区域的向上的Darcy流以及渗透率演变来量化通过2D抗平台剪切模拟地震序列的二维抗平台剪切模拟。当愈合/密封降低断层通透性时，流体过压会在跨界时期发展，并在地震提高渗透性后释放。流体流量，渗透率和压力演化之间的耦合并滑动在地震区域内的基础附近产生流体驱动的无抗震动滑动，而地震发质区域内的地震群，因为上升的流体加压并削弱了断层。该模型可能有助于解释晚期的跨界断层解锁，缓慢的滑移和蠕变瞬变，群震动性以及诱导地震性序列中的快速压力/应力传播。
Fault-zone fluids control effective normal stress and fault strength. While most earthquake models assume a fixed pore fluid pressure distribution, geologists have documented fault valving behavior, that is, cyclic changes in pressure and unsteady fluid migration along faults. Here we quantify fault valving through 2-D antiplane shear simulations of earthquake sequences on a strike-slip fault with rate-and-state friction, upward Darcy flow along a permeable fault zone, and permeability evolution. Fluid overpressure develops during the interseismic period, when healing/sealing reduces fault permeability, and is released after earthquakes enhance permeability. Coupling between fluid flow, permeability and pressure evolution, and slip produces fluid-driven aseismic slip near the base of the seismogenic zone and earthquake swarms within the seismogenic zone, as ascending fluids pressurize and weaken the fault. This model might help explain observations of late interseismic fault unlocking, slow slip and creep transients, swarm seismicity, and rapid pressure/stress transmission in induced seismicity sequences.
