Elastogravity waves and dynamic ground motions in the Korean Peninsula generated by the 11 March 2011 Mw9.0 Tohoku-Oki megathrust earthquake

The mass dislocations caused by large coseismic slips in megathrust earthquakes are large enough to produce elastogravity waves. Despite successful identification of elastogravity-wave development during megathrust earthquakes, the nature of ground motions and hazard potentials in regional and teleseismic distances remains unknown. The dynamic ground motions from the 11 March 2011 MW9.0 Tohoku-Oki megathrust earthquake are retrieved from broadband seismic records throughout the Korean Peninsula. The dynamic ground motions of the megathrust earthquake are dominated by low-frequency (<0.1 Hz) energy that is a mixture of elastogravity waves and seismic waves. The peak dynamic ground displacements in the Korean Peninsula reached ∼20 cm with horizontal permanent displacements of ∼2 cm or more. Radially-polarized elastogravity waves developed instantly at the event origin time. Very-long-period (<0.004 Hz) energy is a mixture of seismic waves and coseismic permanent displacements, prese...