Numerical Modeling of Transient Crustal Deformation in the Korean Peninsula after the 2011 Tohoku Earthquake

The 2011 Tohoku earthquake caused crustal deformations of geodetically observable magnitudes in the Korean peninsula (KP) more than 1000 km away from the epicenter. Since the region's tectonic strain rates are lower than the current detection limits of Global Navigation Satellite System data, the measurable co- and post-seismic crustal deformations provide a rare opportunity to infer the geophysical state of the crust and mantle. The inferred physical state will further contribute to our understanding of the origin of the seismicity in this intraplate region. Reanalyzing the position time series recorded from April 1, 2013 to December 31, 2016 at 55 Global Positioning System stations in South Korea, which were originally processed and made public by Kim et al. (2014), we present the spatial distribution of post-seismic crustal deformations in terms of maximum shear strain rates, principal strain rate orientations, dilation and rotation rates. We also construct numerical models for transient crustal deformations in the KP region using PyLith, a community crustal deformation modeling code. We compute viscoelastic responses of a layered model composed of crust, lithospheric mantle and asthenosphere to one of the slip models for the Tohoku earthquake. The modeled transient deformation rate fields are compared with those derived from the geodetic data and used for constraining the rheology of the region's crust and mantle as well as their heterogeneities in space and time.