TY - JOUR
T1 - 3-D Intrinsic and Scattering Seismic Attenuation Structures Beneath Kyushu, Japan
AU - Shito, A.
AU - Matsumoto, S.
AU - Ohkura, T.
AU - Shimizu, H.
AU - Sakai, S.
AU - Iio, Y.
AU - Takahashi, H.
AU - Yakiwara, H.
AU - Watanabe, T.
AU - Kosuga, M.
AU - Okada, T.
AU - Yoshimi, M.
AU - Asano, Y.
N1 - Funding Information:
The resultant 3‐D and models of this study are available at https://doi.org/10.5281/zenodo.3873789 . The hypocenter information was taken from the SEVO earthquake and JMA‐Unified Hypocenter catalogs. The waveform data used in this study were obtained by Kagoshima University, Kyoto University, Kyushu University, Urgent Joint Seismic Observations of the 2016 Kumamoto Earthquakes, National Research Institute for Earth Science and Disaster Resilience, and JMA. These data are archived at SEVO, Kyushu University, and are available on request (the contact e‐mail address: webmaster@sevo.kyushu‐u.ac.jp ). This work was partly supported by JSPS KAKENHI Grant Numbers 15J40067 and JP18K03807, MEXT, under its Earthquake and Volcano Hazards Observation and Research Program, and the Earthquake Research Institute, The University of Tokyo, under its Joint Usage Program. The Monte Carlo simulation code used in this study is based on the original version provided by Dr. Mitsuyuki Hoshiba, Meteorological Research Institute. We thank Dr. Masashi Ogiso, Meteorological Research Institute, for constructive comments. We also thank Dr. Luca de Siena, an anonymous reviewer, and the Associate Editor for their constructive and insightful comments, which improved the original version of the manuscript.
Funding Information:
The resultant 3-D Qi−1 and Qs−1 models of this study are available at https://doi.org/10.5281/zenodo.3873789. The hypocenter information was taken from the SEVO earthquake and JMA-Unified Hypocenter catalogs. The waveform data used in this study were obtained by Kagoshima University, Kyoto University, Kyushu University, Urgent Joint Seismic Observations of the 2016 Kumamoto Earthquakes, National Research Institute for Earth Science and Disaster Resilience, and JMA. These data are archived at SEVO, Kyushu University, and are available on request (the contact e-mail address: webmaster@sevo.kyushu-u.ac.jp). This work was partly supported by JSPS KAKENHI Grant Numbers 15J40067 and JP18K03807, MEXT, under its Earthquake and Volcano Hazards Observation and Research Program, and the Earthquake Research Institute, The University of Tokyo, under its Joint Usage Program. The Monte Carlo simulation code used in this study is based on the original version provided by Dr. Mitsuyuki Hoshiba, Meteorological Research Institute. We thank Dr. Masashi Ogiso, Meteorological Research Institute, for constructive comments. We also thank Dr. Luca de Siena, an anonymous reviewer, and the Associate Editor for their constructive and insightful comments, which improved the original version of the manuscript.
Publisher Copyright:
©2020. American Geophysical Union. All Rights Reserved.
PY - 2020/8/1
Y1 - 2020/8/1
N2 - The attenuation of seismic wave energy is caused by intrinsic absorption and scattering. The former involves the conversion of seismic wave energy to heat energy via internal friction due to the anelasticity of the medium, whereas the latter involves the scattering of seismic wave energy due to random elastic heterogeneities in the medium. Quantifying both intrinsic ((Formula presented.)) and scattering ((Formula presented.)) attenuation is therefore important for understanding the physical properties of the Earth's interior and predicting seismic wave propagation. Here we develop a new procedure to separately map three-dimensional (3-D) (Formula presented.) and (Formula presented.) structures. The path-averaged (Formula presented.) and (Formula presented.) values are obtained via an envelope-fitting approach that employs a multiple-scattering model. The path-averaged (Formula presented.) and (Formula presented.) structures are then mapped into 3-D space using a tomographic inversion technique based on sensitivity kernels, which are calculated from a Monte Carlo simulation of the radiative transfer equations. We apply this method to map the crustal structure beneath Kyushu, Japan, and obtain 3-D (Formula presented.) and (Formula presented.) structures for the 1–2, 2–4, and 4–8 Hz frequency bands. The spatial attenuation patterns are similar for each of the analyzed frequency bands, with the spatial variability in (Formula presented.) being more pronounced than that in (Formula presented.). The high- (Formula presented.) and (Formula presented.) regions correspond to the locations of active volcanoes. Conversely, the northern Kyushu area possesses low- (Formula presented.) and (Formula presented.) zones that correspond to low heat flow and Cretaceous granite, respectively. The overall (Formula presented.) and (Formula presented.) distributions correlate with thermal and geological structures, respectively.
AB - The attenuation of seismic wave energy is caused by intrinsic absorption and scattering. The former involves the conversion of seismic wave energy to heat energy via internal friction due to the anelasticity of the medium, whereas the latter involves the scattering of seismic wave energy due to random elastic heterogeneities in the medium. Quantifying both intrinsic ((Formula presented.)) and scattering ((Formula presented.)) attenuation is therefore important for understanding the physical properties of the Earth's interior and predicting seismic wave propagation. Here we develop a new procedure to separately map three-dimensional (3-D) (Formula presented.) and (Formula presented.) structures. The path-averaged (Formula presented.) and (Formula presented.) values are obtained via an envelope-fitting approach that employs a multiple-scattering model. The path-averaged (Formula presented.) and (Formula presented.) structures are then mapped into 3-D space using a tomographic inversion technique based on sensitivity kernels, which are calculated from a Monte Carlo simulation of the radiative transfer equations. We apply this method to map the crustal structure beneath Kyushu, Japan, and obtain 3-D (Formula presented.) and (Formula presented.) structures for the 1–2, 2–4, and 4–8 Hz frequency bands. The spatial attenuation patterns are similar for each of the analyzed frequency bands, with the spatial variability in (Formula presented.) being more pronounced than that in (Formula presented.). The high- (Formula presented.) and (Formula presented.) regions correspond to the locations of active volcanoes. Conversely, the northern Kyushu area possesses low- (Formula presented.) and (Formula presented.) zones that correspond to low heat flow and Cretaceous granite, respectively. The overall (Formula presented.) and (Formula presented.) distributions correlate with thermal and geological structures, respectively.
KW - Kyushu
KW - crust
KW - intrinsic attenuation
KW - scattering attenuation
UR - http://www.scopus.com/inward/record.url?scp=85089832074&partnerID=8YFLogxK
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U2 - 10.1029/2019JB018742
DO - 10.1029/2019JB018742
M3 - Article
AN - SCOPUS:85089832074
SN - 2169-9313
VL - 125
JO - Journal of Geophysical Research: Solid Earth
JF - Journal of Geophysical Research: Solid Earth
IS - 8
M1 - e2019JB018742
ER -