We study the rupture process of the 2011 Tohoku megathrust by analyzing
384 regional strong-motion records using a novel back-projection
method for Rayleigh waves with periods between 13 and 100 s. The
proposed approach is based on isolating the signal at the selected
period with a continuous wavelet transform, and generating the stack
using arrival times predicted from detailed fundamental mode Rayleigh
wave group velocity maps. We verify the method by back-projecting
synthetic time series representing a point source off the coast of
Tohoku, which we generate with a 3D finite difference method and
a mesh based on the Japan Integrated Velocity Structure Model. Application
of the method to K-NET/KiK-net records of the Mw 9.1 Tohoku earthquake
reveals several Rayleigh wave emitters, which we attribute to different
stages of rupture. Stage 1 is characterized by slow rupture down-dip
from the hypocenter. The onset of stage 2 is marked by energetic
Rayleigh waves emitted from the region between the JMA hypocenter
and the trench within 60 s after hypocentral time. During stage 3
the rupture propagates bilaterally towards the north and south at
rupture velocities between 3 and 3.5 km/s, reaching Iwate-oki 65
s and Ibaraki-oki 105 s after nucleation. In contrast to short-period
back-projections from teleseismic P-waves, which place radiation
sources below the Honshu coastline, Rayleigh wave emitters identified
from our long-period back-projection are located 50-100 km west of
the trench. This result supports the interpretation of frequency-dependent
seismic wave radiation as suggested in previous studies.
%0 Journal Article
%1 roten_etal:2012
%A Roten, Daniel
%A Miyake, Hiroe
%A Koketsu, Kazuki
%D 2012
%J Geophysical Research Letters
%K geophysics seismology
%N 2
%P L02302+
%R 10.1029/2011GL050183
%T A Rayleigh wave back-projection method applied to the 2011 Tohoku
earthquake
%U http://dx.doi.org/10.1029/2011GL050183
%V 39
%X We study the rupture process of the 2011 Tohoku megathrust by analyzing
384 regional strong-motion records using a novel back-projection
method for Rayleigh waves with periods between 13 and 100 s. The
proposed approach is based on isolating the signal at the selected
period with a continuous wavelet transform, and generating the stack
using arrival times predicted from detailed fundamental mode Rayleigh
wave group velocity maps. We verify the method by back-projecting
synthetic time series representing a point source off the coast of
Tohoku, which we generate with a 3D finite difference method and
a mesh based on the Japan Integrated Velocity Structure Model. Application
of the method to K-NET/KiK-net records of the Mw 9.1 Tohoku earthquake
reveals several Rayleigh wave emitters, which we attribute to different
stages of rupture. Stage 1 is characterized by slow rupture down-dip
from the hypocenter. The onset of stage 2 is marked by energetic
Rayleigh waves emitted from the region between the JMA hypocenter
and the trench within 60 s after hypocentral time. During stage 3
the rupture propagates bilaterally towards the north and south at
rupture velocities between 3 and 3.5 km/s, reaching Iwate-oki 65
s and Ibaraki-oki 105 s after nucleation. In contrast to short-period
back-projections from teleseismic P-waves, which place radiation
sources below the Honshu coastline, Rayleigh wave emitters identified
from our long-period back-projection are located 50-100 km west of
the trench. This result supports the interpretation of frequency-dependent
seismic wave radiation as suggested in previous studies.
@article{roten_etal:2012,
abstract = {We study the rupture process of the 2011 Tohoku megathrust by analyzing
384 regional strong-motion records using a novel back-projection
method for Rayleigh waves with periods between 13 and 100 s. The
proposed approach is based on isolating the signal at the selected
period with a continuous wavelet transform, and generating the stack
using arrival times predicted from detailed fundamental mode Rayleigh
wave group velocity maps. We verify the method by back-projecting
synthetic time series representing a point source off the coast of
Tohoku, which we generate with a 3D finite difference method and
a mesh based on the Japan Integrated Velocity Structure Model. Application
of the method to K-NET/KiK-net records of the Mw 9.1 Tohoku earthquake
reveals several Rayleigh wave emitters, which we attribute to different
stages of rupture. Stage 1 is characterized by slow rupture down-dip
from the hypocenter. The onset of stage 2 is marked by energetic
Rayleigh waves emitted from the region between the JMA hypocenter
and the trench within 60 s after hypocentral time. During stage 3
the rupture propagates bilaterally towards the north and south at
rupture velocities between 3 and 3.5 km/s, reaching Iwate-oki 65
s and Ibaraki-oki 105 s after nucleation. In contrast to short-period
back-projections from teleseismic P-waves, which place radiation
sources below the Honshu coastline, Rayleigh wave emitters identified
from our long-period back-projection are located 50-100 km west of
the trench. This result supports the interpretation of frequency-dependent
seismic wave radiation as suggested in previous studies.},
added-at = {2012-09-01T13:08:21.000+0200},
author = {Roten, Daniel and Miyake, Hiroe and Koketsu, Kazuki},
biburl = {https://www.bibsonomy.org/bibtex/24fc8f6cb4b2ae46702f90f472daf1a98/nilsma},
day = 18,
doi = {10.1029/2011GL050183},
interhash = {9c6f14fa278774329703a9cb4e821b21},
intrahash = {4fc8f6cb4b2ae46702f90f472daf1a98},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {geophysics seismology},
month = jan,
number = 2,
pages = {L02302+},
timestamp = {2021-02-09T13:26:37.000+0100},
title = {A Rayleigh wave back-projection method applied to the 2011 Tohoku
earthquake},
url = {http://dx.doi.org/10.1029/2011GL050183},
volume = 39,
year = 2012
}