Interseismic Masking of Fault Slip Deficit Rates by Earthquake Cycle Processes and Local Block Rotations

Abstract

Abstract Interseismic geodetic observations at active boundaries contain information about tectonic motions and earthquake cycle processes. The combined effects of these two processes may serve to mask tectonic signals near active faults. Motivated by the observation of coseismic rotational motion during the 2016 Mw 7.8 Kaikōura New Zealand earthquake we develop idealized models for the masking of tectonic motions near blocks with local rotation poles. We show that differential interseismic velocities may reach local, rather than far field, maxima contributing to suppression of apparent slip deficit rates. This effect is most pronounced for small (<100 km) tectonic blocks with deep (>10 km) effective locking depths.