Temporal Feasibility of Rapid Joint Inversions in Response to Tsunamis Triggered by Megathrust Earthquakes

Abstract:

Joint inversions of sub-areal surface deformation and tsunami waves generated by seafloor ground motions, while still in their infancy, have the opportunity for realistic representations of megathrust earthquake slip responsible, which occurs primarily offshore. Such joint inversions, including Gusman, et al. [JGR, 2010] and Wei et al. [PAGEOPH, 2014], highlight fault slip unobservable with on land measurements alone. Careful detection of possible slip patterns can affect how nearby communities prepare for future events, therefore their discovery is important for hazard mitigation. Joint inversions could also prove invaluable during a large even through a rapid inversion of real time data. This study looks at the availability and accessibility of land-based GPS and deep-ocean pressure sensor data for rapid join inversions, and the latency between such solutions and both local and global tsunami wave arrivals. We consider GPS rather than other ground-based deformation techniques because of its ability to provide rapid and continuous translations of the ground surface. For tsunami observations, we focus on deep-ocean pressure sensors such as those used in DART systems, because of similarly rapid and continues data availability. Similarly tsunami waves traveling through the deep-ocean have negligible non-linear components, making them ideal for inversion methods. We create a source event in a zone with an elevated seismic risk and then track tsunami travel times to the coast and the nearest deep-ocean pressure sensors to determine a temporal limit to warnings that can be issued to nearby regions. By assessing this latency, focus can be given to areas where an inversion of this type has the potential to improve warning information. This study also identifies regions that lack necessary on and offshore instrumentation to warn coastal communities at risk for tsunamigenic earthquakes. By assessing the feasibility of joint inversions, it becomes easier to move forward with future studies focusing on regions that would see the largest benefit in real-time hazard mitigation.