Shear Strain Energy Change Caused by the Interplate Coupling Along the Nankai Trough: An Integration Analysis Using Stress Tensor Inversion and Slip‐Deficit Inversion

Saito, Tatsuhiko; Noda, Akemi; Yoshida, Keisuke; Tanaka, Sachiko

doi:10.1029/2018jb015839

Cited by 20 publications

(29 citation statements)

References 35 publications

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“…The absolute level of crustal deviatoric stress varies with depth reflecting the state of pressure and temperature (e.g., Brace & Kohlstedt, ; Scholz, ; Shimamoto & Noda, ; Sibson, ), although Saito et al () did not consider the depth dependence in estimating the shear strain energy changes. Considering the linear increase in the frictional strength of defects with depth up to a brittle‐ductile transition zone, we modeled the scale factor γ of

{\overset{true¯}{S}}_{ij}^{'}

as the following function of depth:

γ ()(, z) = μ_{eff} italicρgz (][, 1 - \erf ()(, \frac{z - z_{c}}{\sqrt{2 z_{σ}^{2}}})) / 2 ()(, z > 0) .

…”

Section: Data Models and Resultsmentioning

confidence: 99%

“…To understand earthquake generation in terms of energy accumulation and release in a system, it is well worth evaluating the spatial variation of strain energy in the Earth's crust. To evaluate the strain energy changes associated with an earthquake, we need not only coseismic stress changes but also background crustal stress as known information Saito et al, 2018). We can calculate the coseismic ©2020.…”

Section: Introductionmentioning

confidence: 99%

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The 3‐D Spatial Distribution of Shear Strain Energy Changes Associated With the 2016 Kumamoto Earthquake Sequence, Southwest Japan

Noda

Saito

Fukuyama

et al. 2020

Geophysical Research Letters

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Shear strain energy is an essential physical quantity governing earthquake generation. To calculate the shear strain energy changes due to an earthquake, we need both coseismic stress changes and background crustal stress. The orientation of the background stress can be estimated from earthquake focal mechanisms, but its absolute level is still uncertain. Assuming the level of the background deviatoric stress to be frictional strength in the crust, we evaluated the three‐dimensional distribution of shear strain energy changes associated with the 2016 Kumamoto earthquake sequence, southwest Japan. Its spatial patterns strongly depend on the background stress level. From the energy balance of shear faulting, we proposed that the volume integral of the shear strain energy changes could constrain the background deviatoric stress level. It should be >14 MPa at 10‐km depth at the very least. We showed that approximately 75% of aftershocks occurred where the shear strain energy increased.

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{\overset{true¯}{S}}_{ij}^{'}

as the following function of depth:

γ ()(, z) = μ_{eff} italicρgz (][, 1 - \erf ()(, \frac{z - z_{c}}{\sqrt{2 z_{σ}^{2}}})) / 2 ()(, z > 0) .

…”

Section: Data Models and Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The 3‐D Spatial Distribution of Shear Strain Energy Changes Associated With the 2016 Kumamoto Earthquake Sequence, Southwest Japan

Noda

Saito

Fukuyama

et al. 2020

Geophysical Research Letters

Self Cite

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“…-direction, similar to the driving stress of the Awaji Island earthquake, is induced in the order of a few kPa/yr (seeFig. 5ofSaito et al (2018)). With this in mind, we inferred that…”

mentioning

confidence: 88%

“…Here, the stress field is mixed because of the direction of minimum principal stress induced by the interseismic plate locking deviates from the vertical direction (see Fig. 5 of Saito et al (2018)). We inferred that the stress build-up due to the interseismic plate locking overcame the coseismic stress reduction in a few years, and plays an important role in the occurrence of the northern Osaka earthquake.…”

Section: Stress Transferred By 1995 M W 69 Kobe Earthquakementioning

confidence: 99%

Driving Stress and Seismotectonic Implications of the 2013 Mw5.8 Awaji Island Earthquake, Southwestern Japan, Based on Earthquake Focal Mechanisms Before and After the Mainshock

Imanishi

Ohtani

Uchide

2020

Preprint

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Abstract A driving stress of the M w 5.8 reverse-faulting Awaji Island earthquake (2013), southwest Japan, was investigated using focal mechanism solutions of earthquakes before and after the mainshock. The seismic records from regional high-sensitivity seismic stations were used. Further, the stress tensor inversion method was applied to infer the stress fields in the source region. The results of the stress tensor inversion and the slip tendency analysis revealed that the stress field within the source region deviates from the surrounding area, in which the stress field locally contains a reverse-faulting component with ENE-WSW compression. This local fluctuation in the stress field is key to producing reverse-faulting earthquakes. The existing knowledge on regional-scale stress (tens to hundreds of km) cannot predict the occurrence of the Awaji Island earthquake, emphasizing the importance of estimating local-scale (< tens of km) stress information. It is possible that the local-scale stress heterogeneity has been formed by local tectonic movement, i.e., the formation of flexures in combination with recurring deep aseismic slips. The coseismic Coulomb stress change, induced by the disastrous 1995 M w 6.9 Kobe earthquake, increased along the fault plane of the Awaji Island earthquake; however, the postseismic stress change was negative. We concluded that the gradual stress build-up, due to the interseismic plate locking along the Nankai trough, overcame the postseismic stress reduction in a few years, pushing the Awaji Island earthquake fault over its failure threshold in 2013. The observation that the earthquake occurred in response to the interseismic plate locking has an important implication in terms of seismotectonics in southwest Japan, facilitating further research on the causal relationship between the inland earthquake activity and the Nankai trough earthquake. Furthermore, this study highlighted that the dataset before the mainshock may not have sufficient information to reflect the stress field in the source region due to the lack of earthquakes in that region. This is because the earthquake fault is generally locked prior to the mainshock. Further research is needed for estimating the stress field in the vicinity of an earthquake fault via seismicity before the mainshock alone.

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“…In other words, the earthquake was still likely to occur. Saito et al (2018) computed the stress change at the depth of 10 km due to the interseismic plate locking along the Nankai trough (slip de cit) estimated using the GNSS data (Noda et al 2017). This showed that around the source region, a reverse faulting stress change with the -direction, similar to the driving stress of the Awaji Island earthquake, is induced in the order of a few kPa/yr (see Fig.…”

Section: Stress Transferred By 1995 Mw69 Kobe Earthquakementioning

confidence: 99%

Driving stress and seismotectonic implications of the 2013 Mw5.8 Awaji Island earthquake, southwestern Japan, based on earthquake focal mechanisms before and after the mainshock

Imanishi

Ohtani

Uchide

2020

Preprint

View full text Add to dashboard Cite

A driving stress of the M w 5.8 reverse-faulting Awaji Island earthquake (2013), southwest Japan, was investigated using focal mechanism solutions of earthquakes before and after the mainshock. The seismic records from regional high-sensitivity seismic stations were used. Further, the stress tensor inversion method was applied to infer the stress fields in the source region. The results of the stress tensor inversion and the slip tendency analysis revealed that the stress field within the source region deviates from the surrounding area, in which the stress field locally contains a reverse-faulting component with ENE-WSW compression. This local fluctuation in the stress field is key to producing reverse-faulting earthquakes. The existing knowledge on regional-scale stress (tens to hundreds of km) cannot predict the occurrence of the Awaji Island earthquake, emphasizing the importance of estimating local-scale (< tens of km) stress information. It is possible that the local-scale stress heterogeneity has been formed by local tectonic movement, i.e., the formation of flexures in combination with recurring deep aseismic slips. The coseismic Coulomb stress change, induced by the disastrous 1995 M w 6.9 Kobe earthquake, increased along the fault plane of the Awaji Island earthquake; however, the postseismic stress change was negative. We concluded that the gradual stress build-up, due to the interseismic plate locking along the Nankai trough, overcame the postseismic stress reduction in a few years, pushing the Awaji Island earthquake fault over its failure threshold in 2013. The observation that the earthquake occurred in response to the interseismic plate locking has an important implication in terms of seismotectonics in southwest Japan, facilitating further research on the causal relationship between the inland earthquake activity and the Nankai trough earthquake. Furthermore, this study highlighted that the dataset before the mainshock may not have sufficient information to reflect the stress field in the source region due to the lack of earthquakes in that region. This is because the earthquake fault is generally locked prior to the mainshock. Further research is needed for estimating the stress field in the vicinity of an earthquake fault via seismicity before the mainshock alone.

show abstract

Shear Strain Energy Change Caused by the Interplate Coupling Along the Nankai Trough: An Integration Analysis Using Stress Tensor Inversion and Slip‐Deficit Inversion

Cited by 20 publications

References 35 publications

The 3‐D Spatial Distribution of Shear Strain Energy Changes Associated With the 2016 Kumamoto Earthquake Sequence, Southwest Japan

The 3‐D Spatial Distribution of Shear Strain Energy Changes Associated With the 2016 Kumamoto Earthquake Sequence, Southwest Japan

Driving Stress and Seismotectonic Implications of the 2013 Mw5.8 Awaji Island Earthquake, Southwestern Japan, Based on Earthquake Focal Mechanisms Before and After the Mainshock

Driving stress and seismotectonic implications of the 2013 Mw5.8 Awaji Island earthquake, southwestern Japan, based on earthquake focal mechanisms before and after the mainshock

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