Tsunami Simulation by Tuned Seismic Source Inversion for the Great 2011 Tohoku
and K. I
Abstract—Seismic and tsunami waves were the most destruc-
tive phenomena during the 2011 Tohoku earthquake. Here we ask
whether the same source model can be used to obtain equally good
simulations of the observed strong ground motions and the tsunami
waves. If so, we could use the same source modeling technique for
predictions of both tsunami waves and strong ground motions.
Long-period (20–200 s) strong ground motion data were inverted
to determine the rupture process of the 2011 Tohoku earthquake.
The inverted slip distribution shows that large-slip area was
extended around 150 km to north and 120 km to south from
hypocenter and stretched between hypocenter and the trench. We
estimated two slip models: without and with additional constraints.
The ﬁrst relatively rough slip model reproduced short-period tsu-
nami wave (4–5 min). Due to better constraint by data of other kind
and being relatively smooth the second model reproduces long-
period tsunami wave (15–25 min), as well as keeps good ﬁt of the
short-period tsunami, although short-period tsunami becomes
underestimated. We used a fully nonlinear Boussinesq water wave
model to model tsunami propagation, and used the results to tune
the slip model. Finally, we developed a tuned slip model that
combines the features of both the ﬁrst and the second slip models
and reproduced both the short- and long-period tsunami waves,
while maintaining good ﬁt of the seismic waveforms.
Key words: 2011 Tohoku earthquake, source inversion, fully
nonlinear tsunami simulation.
On 11 March 2011, an Mw9.0 earthquake occur-
red off the Paciﬁc coast of Tohoku, Japan, as a result
of thrust faulting on the interface between the Paciﬁc
and North America plates. This earthquake generated
a 30- to 40-m extremely high run-up in central and
north Sanriku coast of Japan. The high run-up was
associated with unusual short-period tsunami wave
(e.g., Shimozono et al. 2014). This earthquake also
generated strong ground motion of the order
in high-frequency range. It is one of the
best geophysically recorded earthquakes among great
earthquakes. Numerous source models have been
generated by using teleseismic, GPS, strong ground
motion, and tsunami data (e.g., Hayes 2011; Ide et al.
2011; Ito et al. 2011; Lay et al. 2011; Satake et al.
2013; see review Tajima et al. 2013).
Here we ask whether the same source model can
be used to obtain equally good simulations of the
observed ground motions and tsunami waves. If so, it
would be possible to use source modeling techniques
that have been developed for strong-motion predic-
tion, for modeling of tsunami sources and to predict
possible tsunamis as well. For example, Irikura and
Miyake (2011) employ source scaling for inland
earthquakes based on seismic inversion results (see
Somerville et al. 1999; Murotani et al. 2015, and
references therein). For subduction earthquakes such
scaling was developed by Murotani et al. 2008).
Seismic source modeling is based on the determina-
tion of scaling relations between source parameters
such as fault area, slip asperity (large slip) area, slip
magnitude, and seismic moment (Murotani et al.
2008). These scaling relations are estimated by the
generalization of seismic source inversion results. In
this study, we applied a seismic source inversion
technique for modeling tsunami sources and tested it
on a megathrust earthquake (the 2011 Tohoku
earthquake) by comparing simulated and observed
Inversion techniques using seismic wave data
have been applied successfully to subduction
Geo-Research Institute, 6F, Kokuminkaikan Sumitomo-
seimei Bldg., 2-1-2 Otemae, Chuo-ku, Osaka 540-0008, Japan.
Aichi Institute of Technology, 1247 Yachigusa, Yakusa,
Toyota, Aichi 470-0392, Japan.
Pure Appl. Geophys. 174 (2017), 2891–2908
Ó 2017 Springer International Publishing AG
Pure and Applied Geophysics