The 2011 Mw 9.0 Tohoku-Oki megathrust earthquake accompanied coseismic and postseismic displacements around the eastern Eurasian continental plate. Noise cross correlations produced transient seismic waveforms along interstation paths in the Korean Peninsula. We measured the traveltime changes of the fundamental mode Rayleigh waves over the range of 0.03–0.08 Hz after the megathrust earthquake. The temporal seismic velocity changes in the lower crust were assessed from the traveltime changes. The traveltimes increased instantly after the megathrust earthquake and were gradually recovered over several hundreds to thousands of days. The instant shear wave velocity decreases ranged between 0.731 (±0.057)% and 4.068 (±0.173)%. The temporal medium perturbation might be caused by the transient uniaxial tensional stress due to the coseismic and postseismic displacements. The medium properties may be recovered by progressive stress field reconstruction.
Bibliographical noteFunding Information:
Most analysis results are presented in the supporting information. The continuous seismic waveform records and station information are available from Korea Meteorological Administration (necis.kma.go.kr). The authors are grateful to Andrew Newman (Editor) and two anonymous reviewers for valuable review comments that improved the presentation of this manuscript. This work was supported by the Korea Meteorological Administration Research and Development Program under grant KMIPA 2015-7040. In addition, this research was partly supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2017R1A6A1A07015374).
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All Science Journal Classification (ASJC) codes
- Earth and Planetary Sciences(all)