TY - JOUR A1 - Pina-Valdes, Jesus A1 - Socquet, Anne A1 - Cotton, Fabrice Pierre T1 - Insights on the Japanese Subduction Megathrust Properties From Depth and Lateral Variability of Observed Ground Motions JF - Journal of geophysical research : Solid earth N2 - Two ground motion prediction equation models for subduction zones have been tested using a public ground motion database of the KiK-net records obtained by automated processing protocols (Dawood et al., 2016, https://doi.org/10.1193/071214EQS106). The database contains records of more than 700 interface earthquakes that occurred on the Japan subduction between 1998 and 2012. The Zhao et al. (2006, https://doi.org/10.1785/0120050122) ground motion prediction equation was shown to be the best suited model for the region. It was then used as backbone to analyze the variability of ground motion records. The residuals between observed and predicted ground motions have been analyzed to study the spatial variation of the earthquakes' ground motion frequency content on the Japan megathrust. This analysis revealed a depth dependency of generated ground motions consistent with the downdip segmentation proposed for subduction interfaces (Lay et al., 2012, https://doi.org/10.1029/2011JB009133), a regional ground motion dependency that may be related with lateral variations of the mechanical properties of the subduction interface and a high-frequency radiations drop in the earthquake sequence that preceded the Tohoku-Oki earthquake Mw 9.0. The regional ground motion dependency suggests the existence of different domains along trench of the Japan subduction megathrust that control the ground motions and the wave radiation patterns of interface earthquakes. The location of their boundaries is consistent with the extension of the rupture of the 2011 Tohoku-Oki earthquake, with pre-Tohoku interseismic coupling, and with the free air gravity anomalies. KW - ground motion KW - Japan subduction zone KW - ground motion prediction equations KW - subduction interface Y1 - 2018 U6 - https://doi.org/10.1029/2018JB015743 SN - 2169-9313 SN - 2169-9356 VL - 123 IS - 10 SP - 8937 EP - 8956 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Pina-Valdes, Jesus A1 - Socquet, Anne A1 - Cotton, Fabrice Pierre A1 - Specht, Sebastian T1 - Spatiotemporal Variations of Ground Motion in Northern Chile before and after the 2014 M-w 8.1 Iquique Megathrust Event JF - Bulletin of the Seismological Society of America N2 - To evaluate the spatiotemporal variations of ground motions in northern Chile, we built a high-quality rock seismic acceleration database and an interface earthquakes catalog. Two ground-motion prediction equation (GMPE) models for subduction zones have been tested and validated for the area. They were then used as backbone models to describe the time-space variations of earthquake frequency content (Fourier and response spectra). Consistent with previous studies of large subduction earthquakes, moderate interface earthquakes in northern Chile show an increase of the high-frequency energy released with depth. A regional variability of earthquake frequency content is also observed, which may be related to a lateral segmentation of the mechanical properties of the subduction interface. Finally, interface earthquakes show a temporal evolution of their frequency content in the earthquake sequence associated with the 2014 Iquique M-w 8.1 megathrust earthquake. Surprisingly, the change does not occur with the mainshock but is associated with an 8 month slow slip preceding the megathrust. Electronic Supplement: Strong-motion database. Y1 - 2018 U6 - https://doi.org/10.1785/0120170052 SN - 0037-1106 SN - 1943-3573 VL - 108 IS - 2 SP - 801 EP - 814 PB - Seismological Society of America CY - Albany ER -