Lithospheric structure in and around Slow Slip in the Alaska Subduction Region

Abstract

<p>Subduction zones host some of the greatest megathrust earthquakes in the world. Slow earthquakes have been also discovered around the subduction zones of the Pacific rim very close to megathrust earthquakes in several subduction zones in Chile, Cascadia, Mexico, Alaska, and New Zealand (Obara and Kato, 2016). Investigating the lithosphere of the slow earthquake area versus non slow-earthquake areas in subduction zones is crucial in understanding the role of the internal structure to control slow earthquakes. Deep transient slow slip had been detected in the Lower and Upper Cook Inlet in the Alaska subduction region(Fu et al. 2015; Li et al. 2016; Wei et al. 2012). In this study, we investigate the lithospheric structure beneath the stations in and around the slow earthquake area in Alaska. We also study the non slow-earthquake areas in the Alaska subduction zone using receiver function analysis and inversion method using teleseismic earthquakes. Here we focus on, especially the Vs and Vp/Vs ratios from both the slow and non-slow earthquake areas, because of the sensitivity  to the fluid distribution in the lithosphere; the fluid distribution possibly controls the potential occurrence of slow earthquakes.<br>Additionally, the nature of the slab can also play a crucial factor. The velocities around the plate interface region in the lower continental mantle, subducted oceanic crust and upper oceanic mantle has the potential to reveal information that the structural heterogeneity could be related to the slow slip.</p>