A physical mechanism for temporal variation in seismicity in Southwest Japan related to the great interplate earthquakes along the Nankai trough

Hori, Takane; Oike, Kazuo

doi:10.1016/s0040-1951(99)00079-7

Cited by 30 publications

(21 citation statements)

References 22 publications

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“…Then, the change in normal stress on the plane normal to N100°E, Δ σ NKTZ , is expressed as

Δ σ_{NKTZ} = E Δ ε_{NKTZ}

where E is the Young's modulus (100 GPa), which is calculated from the structural parameters given in section 2.1. The stress accumulation rate due to NKTZ compression, Δ σ NKTZ , is 3 kPa/yr, which is consistent with the stress accumulation rate for “A class” inland active faults in Japan (average slip rate higher than 1 mm/yr) [ Hori and Oike , ]. For simplicity, the principal stress components other than Δ σ NKTZ are assumed to be zero.…”

Section: Model For δCff Calculationsmentioning

confidence: 87%

Long‐term changes in the Coulomb failure function on inland active faults in southwest Japan due to east‐west compression and interplate earthquakes

2014

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Inland earthquake activity in and around the Kinki region, southwest Japan, increases in the period from several decades before to about a decade after the occurrence of great interplate earthquakes along the Nankai Trough. To quantitatively investigate this relationship, we calculated long-term changes in the Coulomb failure function (ΔCFF) on inland active faults in this region with viscoelastic slip response functions. As sources for the change in CFF, we investigated east-west compression within the Niigata-Kobe Tectonic Zone (NKTZ), historical interplate earthquakes and interseismic locking along the Nankai Trough subduction zone, and historical inland earthquakes in this region. Among these sources, the NKTZ east-west compression is the primary cause of the long-term changes in CFF. The changes in CFF due to interplate earthquakes are mostly negative on reverse faults and positive on strike-slip faults. This result suggests that the inland reverse faulting activity mostly increases before interplate earthquakes and decreases after the earthquakes, whereas strike-slip activity is mostly suppressed before interplate earthquakes and increases thereafter. This suggestion is supported by spatiotemporal pattern of historical inland earthquakes if focal mechanisms of historical earthquakes correspond to fault geometries in the region. The calculated changes in CFF are usually consistent with the occurrence of historical inland earthquakes. If we use the change in shear stress instead of the change in CFF, this consistency is enhanced, which suggests low apparent coefficients of friction in this region.

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“…Then, the change in normal stress on the plane normal to N100°E, Δ σ NKTZ , is expressed as

Δ σ_{NKTZ} = E Δ ε_{NKTZ}

Section: Model For δCff Calculationsmentioning

confidence: 87%

Long‐term changes in the Coulomb failure function on inland active faults in southwest Japan due to east‐west compression and interplate earthquakes

2014

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“…The active seismic period in western Japan before each great interplate event is constant around 50 years, while the quiet period is dependent on the size of the last event, lasting 50 years or more [ Mogi , 1981; Hori and Oike , 1996]. Likewise, Hori and Oike [1999] showed that one way causal effect from the great events to the inland earthquakes was significant based on the simulation study of static stress changes and increase in tectonic stress on the faults and the plate boundary.…”

Section: Introductionmentioning

confidence: 99%

Seismicity quiescence and activation in western Japan associated with the 1944 and 1946 great earthquakes near the Nankai trough

Ogata

2004

J. Geophys. Res.

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Significant changes in seismicity (quiescence and activation) took place during the period of 1944–1946 in some regions in western Japan. They are well explained by the corresponding changes in Coulomb failure stress caused by the 1944 Tonankai earthquake of M7.9 and the 1946 Nankai earthquake of M8.0, both of which occurred in the Nankai trough. From the seismicity changes I try to identify precursory anomalies such as the quiescence in several regions before the Tonankai event and the enhanced activity in southern Kii peninsula before the Nankai event. These quiescence and enhanced activity may be due to precursory aseismic slips in an area on the plate interface downdip of the Tonankai rupture and slips transferring from the Tonankai to Nankai rupture zone. The records of felt shocks at the Wakayama Observatory during 1900–1995 provide support for the quiescence in the Wakayama District during 1944–1946, as well as a scenario of seismicity cycle till the next great event(s) in the Nankai trough to occur sometime this century.

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“…geophys., period from several decades before to a decade after the occurrence of the great interplate earthquakes (HORI and OIKE, 1996). As a mechanism explaining the temporal correlation between the intraplate earthquakes and interplate ones in SWJ, it has been suggested that the stress perturbation due to the earthquake cycles along the Nankai trough affect the steady tectonic east-west loading on inland faults (e.g., HORI and OIKE, 1999). However, this model is based on the purely elastic medium, and the strong structural heterogeneity and viscoelasticity, which are characteristic of subduction zones, are not taken into consideration.…”

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confidence: 99%

GeoFEM Kinematic Earthquake Cycle Simulation in Southwest Japan

Hyodo

Hirahara

2004

Pure appl. geophys.

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We construct a viscoelastic FEM model with 3-D configuration of the subducting Philippine Sea plate in Southwest Japan to simulate recent 300-year kinematic earthquake cycles along the Nankai-Suruga-Sagami trough, based on the kinematic earthquake cycle model. This 300-year simulation contains a series of three great interplate earthquakes. The inclusion of viscoelasticity produces characteristic velocity field during earthquake cycles regardless of the assumed constant plate coupling throughout the interseismic period. Just after the occurrence of interplate earthquakes, the viscoelastic relaxation creates the seaward motion in the inland region. In the middle period, the seaward motion gradually decreases, and the resultant velocity field is similar to the elastic one. Later, just before the next interplate earthquake, displacements due to the interplate coupling in the viscoelastic material are distributed more broadly in the forearc region than in the purely elastic one, since the viscoelastic relaxation due to the previous earthquake mostly disappears. The effects of such interplate earthquake cycles on five major inland faults in southwest Japan, where large intraplate earthquakes occurred during this period, are quantitatively evaluated using the Coulomb failure function (CFF). The calculated change in CFF successfully predicts the occurrence of the 1995 Kobe earthquake (M$7). The occurrence of other inland earthquakes, however, cannot be explained by the calculated changes in CFF, and especially the 1891 Nobi earthquake (M$8), the largest inland earthquake in Japan, which occurred at the time close to the local minimum of CFF. This implies that further improvements are necessary for our FEM modeling, such as the modeling of steady east-west compressive force and stress interactions between the inland faults.

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A physical mechanism for temporal variation in seismicity in Southwest Japan related to the great interplate earthquakes along the Nankai trough

Cited by 30 publications

References 22 publications

Long‐term changes in the Coulomb failure function on inland active faults in southwest Japan due to east‐west compression and interplate earthquakes

Long‐term changes in the Coulomb failure function on inland active faults in southwest Japan due to east‐west compression and interplate earthquakes

Seismicity quiescence and activation in western Japan associated with the 1944 and 1946 great earthquakes near the Nankai trough

GeoFEM Kinematic Earthquake Cycle Simulation in Southwest Japan

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