A coupled fluid-fracture approach to propagation of clastic dikes during earthquakes

摘要

The propagation of clastic dikes was studied in Ami'az Plain, where hundreds of clastic dikes cross-cut the soft rock of the late Pleistocene lacustrine Lisan Formation, within the seismically active Dead Sea basin. Two analytic models were established to estimate the dike propagation velocities, the dike emplacement duration, and the driving pressures that were associated with dike propagation either under laminar or turbulent flow conditions. These models depend on the host-rock and fluid properties, dike width and length. Based on these properties and field limitations, the results indicate that the dikes were propagated under turbulent flow conditions and propagation velocities of ~. 4-65. m/s. The emplacement duration of the clastic dikes is between ~. 0.8 and 2. s, which is similar to the order of the acoustic wave duration that passes through the soft rock during an earthquake event. This implies that the propagation of dikes could form during the passing acoustic waves and may thus be considered as an earthquake-induced impact structures. The calculated driving pressures that were generated during the earthquake events near the surface are 1-2. MPa, one order of magnitude larger than the pressure due to the overburden on the source layer.