TY - JOUR
T1 - Sensitivity Analysis for Seafloor Geodetic Constraints on Coseismic Slip and Interseismic Slip-Deficit Distributions
AU - Murakami, Sota
AU - Ichimura, Tsuyoshi
AU - Fujita, Kohei
AU - Hori, Takane
AU - Ohta, Yusaku
N1 - Funding Information:
We thank the two anonymous reviewers for constructive comments. Digital data of surface topography, plate boundary and coseismic slip distribution are given by Cabinet Office, Disaster Management. This work was supported by the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT) as “Program for Promoting Researches on the Supercomputer Fugaku” (Large-scale numerical simulation of earthquake generation, wave propagation and soil amplification: hp200126) and by JSPS KAKENHI (JP18H05239). This work was partly supported by MEXT, under its Earthquake and Volcano Hazards Observation and Research Program.
Funding Information:
We thank the two anonymous reviewers for constructive comments. Digital data of surface topography, plate boundary and coseismic slip distribution are given by Cabinet Office, Disaster Management. This work was supported by the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT) as “Program for Promoting Researches on the Supercomputer Fugaku” (Large-scale
Funding Information:
This work was supported by the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT) as “Program for Promoting Researches on the Supercomputer Fugaku” (Large-scale numerical simulation of earthquake generation, wave propagation and soil amplification: hp200126) and by JSPS KAKENHI (JP18H05239).
Publisher Copyright:
© Copyright © 2021 Murakami, Ichimura, Fujita, Hori and Ohta.
PY - 2021/4/21
Y1 - 2021/4/21
N2 - Estimating the coseismic slip distribution and interseismic slip-deficit distribution play an important role in understanding the mechanism of massive earthquakes and predicting the resulting damage. It is useful to observe the crustal deformation not only in the land area, but also directly above the seismogenic zone. Therefore, improvements in terms of measurement precision and increase in the number of observation points have been proposed in various forms of seafloor observation. However, there is lack of research on the quantitative evaluation of the estimation accuracy in cases where new crustal deformation observation points are available or when the precision of the observation methods have been improved. On the other hand, the crustal structure models are improving and finite element analysis using these highly detailed crustal structure models is becoming possible. As such, there is the real possibility of performing an inverted slip estimation with high accuracy via numerical experiments. In view of this, in this study, we proposed a method for quantitatively evaluating the improvement in the estimation accuracy of the coseismic slip distribution and the interseismic slip-deficit distribution in cases where new crustal deformation observation points are available or where the precision of the observation methods have been improved. As a demonstration, a quantitative evaluation was performed using an actual crustal structure model and observation point arrangement. For the target area, we selected the Kuril Trench off Tokachi and Nemuro, where M9-class earthquakes have been known to occur in the past and where the next imminent earthquake is anticipated. To appropriately handle the effects of the topography and plate boundary geometry, a highly detailed three-dimensional finite element model was constructed and Green’s functions of crustal deformation were calculated with high accuracy. By performing many inversions via optimization using Green’s functions, we statistically evaluated the effect of increase in the number of observation points of the seafloor crustal deformation measurement and the influence of measurement error, taking into consideration the diversity of measurement errors. As a result, it was demonstrated that the observation of seafloor crustal deformation near the trench axis plays an extremely important role in the estimation performance.
AB - Estimating the coseismic slip distribution and interseismic slip-deficit distribution play an important role in understanding the mechanism of massive earthquakes and predicting the resulting damage. It is useful to observe the crustal deformation not only in the land area, but also directly above the seismogenic zone. Therefore, improvements in terms of measurement precision and increase in the number of observation points have been proposed in various forms of seafloor observation. However, there is lack of research on the quantitative evaluation of the estimation accuracy in cases where new crustal deformation observation points are available or when the precision of the observation methods have been improved. On the other hand, the crustal structure models are improving and finite element analysis using these highly detailed crustal structure models is becoming possible. As such, there is the real possibility of performing an inverted slip estimation with high accuracy via numerical experiments. In view of this, in this study, we proposed a method for quantitatively evaluating the improvement in the estimation accuracy of the coseismic slip distribution and the interseismic slip-deficit distribution in cases where new crustal deformation observation points are available or where the precision of the observation methods have been improved. As a demonstration, a quantitative evaluation was performed using an actual crustal structure model and observation point arrangement. For the target area, we selected the Kuril Trench off Tokachi and Nemuro, where M9-class earthquakes have been known to occur in the past and where the next imminent earthquake is anticipated. To appropriately handle the effects of the topography and plate boundary geometry, a highly detailed three-dimensional finite element model was constructed and Green’s functions of crustal deformation were calculated with high accuracy. By performing many inversions via optimization using Green’s functions, we statistically evaluated the effect of increase in the number of observation points of the seafloor crustal deformation measurement and the influence of measurement error, taking into consideration the diversity of measurement errors. As a result, it was demonstrated that the observation of seafloor crustal deformation near the trench axis plays an extremely important role in the estimation performance.
KW - crustal deformation
KW - finite element analysis
KW - inversion of fault slip
KW - seafloor observation
KW - sensitivity analysis
KW - Tokachi-oki earthquake
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U2 - 10.3389/feart.2021.614088
DO - 10.3389/feart.2021.614088
M3 - Article
AN - SCOPUS:85105371522
SN - 2296-6463
VL - 9
JO - Frontiers in Earth Science
JF - Frontiers in Earth Science
M1 - 614088
ER -