IOP Conference Series: Earth and Environmental Science | 2021
Dynamics of dip-slip fault rupture
Abstract
This contribution summarizes our recent findings related to the dynamics of shallow dip-slip earthquakes, especially that of the asymmetric seismic motion in hanging walls and footwalls. First, by means of experimental dynamic photoelasticity and numerical finite difference simulations, dynamic rupture of a relatively large fault plane near a free surface is studied. It is found, for instance, that upon surfacing of the primary upward fault rupture, Rayleigh surface waves traveling outwards to the far-field and Rayleigh-type interface waves moving downwards back to the source can be induced. For an inclined fault plane, these Rayleigh and interface waves can interact with each other in the hanging wall to produce a “corner” shear wave with concentrated energy and thus the asymmetric seismic motion. Then, instead of considering only one single large-scale fault plane, more geometrically complex dip-slip faults that consist of damage zones with sets of smaller-scale parallel cracks are examined. The photoelastic study shows that depending on the dip angle, the rupture behavior may differ considerably. For a larger dip angle, secondary and further downward ruptures can be initiated, arrested and resume dynamic movement even without additional external load, seemingly due to the dynamic waves caused by the primary upward rupture.