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Friday July 1, 2022
Andrea Perez-Silva, Victoria University of Wellington
Over the last two decades, geodetic observations have revealed slow slip events (SSEs) in most subduction zones worldwide. Of these, SSEs that occur along the shallow (<~15 km depth) portion of the Hikurangi margin (New Zealand) are one of the most well monitored and documented. Two intriguing and as of yet poorly understood observations of shallow Hikurangi SSEs have been made recently. First, their recurrence intervals are strongly segmented along the Hikurangi margin, varying from ~5 yrs to ~1 yr. Second, pore fluid pressure in the vicinity of the megathrust fault has been inferred to cyclically vary during these SSEs. In this seminar I will discuss how two different numerical models, both applying boundary integral element method (BIEM) and within rate-and-state framework, may give insight into the mechanisms that explain these observations. Our modeling results suggest that the geometry of the subducting plate at Hikurangi may play an important role in the segmentation of SSE recurrence interval. They also indicate that pore-pressure cycling may trigger SSEs with realistic source properties. These findings may contribute to our understanding of slow slip behavior in other subduction zones.