JpGU-AGU Joint Meeting 2017

Presentation information

[EE] Poster

S (Solid Earth Sciences) » S-SS Seismology

[S-SS08] [EE] Earthquake Modeling and Simulation

Mon. May 22, 2017 10:45 AM - 12:15 PM Poster Hall (International Exhibition Hall HALL7)

convener:Eiichi Fukuyama(National Research Institute for Earth Science and Disaster Prevention), John B Rundle(University of California Davis), Yukitoshi Fukahata(Disaster Prevention Research Institute, Kyoto University)

[SSS08-P11] Regional earthquake induction around the Korean Peninsula after the 2011 M9.0 Tohoku-Oki megathrust earthquake

*Tae-Kyung Hong1, Junhyung Kim1, Seongjun Park1 (1.Department of Earth System Sciences, Yonsei University)

Megathrust earthquakes produce large permanent
lithospheric displacements as well as strong transient
ground shaking up to regional distances. The lateral
permanent displacements construct stress shadows in a
wide backarc region. The Korean Peninsula is placed in
the far-eastern Eurasian plate that belongs to a stable
intraplate region with a low earthquake occurrence rate
and diffused seismicity, and is located in the backarc at
~1300 km in the west from the epicenter of the 11 March
2011 M9.0 Tohoku-Oki earthquake. The seismicity around
the Korean Peninsula was increased significantly after
the 2011 M9.0 Tohoku-Oki earthquake. Strong seismic waves
cause large dynamic stress changes, incurring fluid
migration and increasing pore fluid pressure in the
media. The lithospheric displacements directing to the
epicenter on the convergent plate boundary develop
transient radial tension field over the backarc
lithospheres. The seismic velocities in the lithosphere
changed abruptly up to 2 % after the megathrust
earthquake, which recovered gradually with time for
several years. A series of moderate-sized earthquakes and
earthquake swarms occur as a consequence of medium
response to the temporal evolution of stress field. In
particular, two strike-slip earthquakes with magnitudes
of ML5.1 and 5.8 occurred in the southeastern Korean
Peninsula on September 12, 2016. The two events occurred
within 48 minutes. The ML5.8 earthquake was the
largest event in the Korean Peninsula since 1978 when
national seismic monitoring began. More than 500
aftershocks with local magnitudes greater than or equal
to 1.5 followed the events for two months. The long-term
evolution of seismicity is expected to continue until the
ambient stress field is fully recovered.