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We investigate the complex rupture properties of the 2016 Mw 7.8 Kaikōura earthquake by jointly inverting teleseismic body-wave and regional Global Positioning System (GPS) coseismic deformation data within a multifault model. We validate our results by forward modeling recorded Interferometric Synthetic Aperture Radar (InSAR) interferograms. Our study reveals the complementary depth-dependent contributions of teleseismic and local geodetic data to the cumulative slip distribution. The resulting joint inversion model of the rupture process and slip pattern explains both the far-field (teleseismic data) and near-field (GPS and InSAR data) observations. The model highlights variable rupture velocity throughout the sequence, with an initial high-velocity (2.25 km/s) pulse followed by slow (~1.5 km/s) yet significant reverse and transverse motion on faults stretching at least 160 km to the north of the origin. We map significant thrust motion on a dipping plane representing the combined effects of the Hope, Hundalee, and Jordan thrust faults as well as large strike-slip motion along the Kekerengu and Needles faults. The mainshock also ruptured the deep portion of the subduction interface at a velocity of 1.0 km/s. [ABSTRACT FROM AUTHOR]

We investigated broadband evidence of the rupture directivity effect and estimated stress drop for the 2013 Nantou blind-thrust earthquakes (the 0327 and 0602 crustal events) from three individual analyses using empirical Green's functions: deconvolution source time function analysis, source spectral ratio analysis, and broadband waveform modeling of a strong-motion generation area. Although these two adjacent events have similar focal mechanisms, the 0327 event shows only up-dip directivity to the west, with an estimated stress drop of 9.0 MPa, and the 0602 event displays significant rupture directivity to the southwest, with an estimated stress drop of 14.2 MPa. The obvious variance in the rupture behavior and stress drop of these two nearby events, which might be related to immature blind faulting, suggests that this region requires additional study of the stress heterogeneity to better assess the seismic hazard. [ABSTRACT FROM AUTHOR]

From the end of August to early September 2011, 15 ocean-bottom seismometers (OBSs) were deployed offshore northeastern Taiwan for approximately 20 days. During this period, the typhoon Nanmadol formed in the western Pacific, moved northwestward from the East Philippines, and made landfall on the island of Taiwan. In this study, we analyzed the seismic signals from the OBSs and the marine metrological data to investigate the influence of the typhoon on submarine seismic records. Our results show that the signals induced by the typhoon occurred mainly at approximately 0.15-0.5 Hz frequency. The magnitude of these signals depends substantially on water depth. Some exceptions, most likely generated by site effects, were observed. Also, a positive correlation exists between the signals energy and the local wave height, which suggests that the microseisms were affected by the pressure changes produced by the local wave activity as the typhoon passed over the stations. However, when an OBS was outside the typhoon periphery, any wave energy variations could only be caused by the elastic wave formed around the typhoon area, the energy of which is transmitted through the ocean bottom to the stations. Thus, no local waves were excited by the strong winds, and only a relatively small amount of energy was recorded. [ABSTRACT FROM AUTHOR]

The rupture process and tectonic surroundings of the 2008 Wenchuan, China, earthquake are both complex in a way that might be related to the heterogeneous stress field of the Longmen Shan region. In this study, we construct dynamic models with heterogeneous initial stress to reproduce a kinematic inversion result by Wen et al. (2012) and investigate the physical mechanisms of the variable slip pattern and rupture velocity in this event. The results show that, for the 2008 Wenchuan earthquake, (1) the rupture behavior and slip pattern can be explained by heterogeneities in initial stress and (2) the variations of rupture velocity and ground-motion pattern are strongly affected by both stress drop and fault strength. Our preferred dynamic model agrees with the kinematic model that the 2008 Wenchuan earthquake initiated with a slow velocity in the southwest, sped up in the segment with the largest slip, and then slowed down for the remaining propagation to the northeast. [ABSTRACT FROM AUTHOR]