The role of fault continuity at depth in numerical simulations of earthquake rupture

概要

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We simulated dynamic rupture propagation along a branched fault, which is partially segmented by a slit. This is an analogy of a strike slip fault, which displays a jog structure on the ground surface but forms a continuous system at depth. We observed that rupture directivity can significantly change due to the existence of the fault slit and that the relative location of the slit to the hypocenter is important. On the other hand, final rupture area and slip distribution are principally controlled by the continuity of the fault at depth. However, if the continuous part of the fault is too narrow, the rupture can be disturbed. If enough stress is accumulated, rupture can still progress through a strong dynamic stress transfer at the bottom of the slit. This infers that it is important to reveal the fault structure at depth and its surroundings in order to discuss rupture size in a complex fault system in the geological meaning.