Coseismic Slip Distribution of the 2005 Miyagi-Oki (M 7.2) Earthquake Estimated by Inversion of Strong-motion and Teleseismic Waveforms

直, 柳沼; 知己, 岡田; 昭, 長谷川; 研一, 加藤; 雅之, 武村; 勇治, 八木

doi:10.4294/zisin.60.43

Cited by 6 publications

(5 citation statements)

References 11 publications

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“…We propose that this elongate slip distribution that is parallel to the slip direction is a common feature of earthquakes in the Tohoku-Hokkaido subduction zone. This interpretation is supported by the slip distributions of larger earthquakes, such as the 2003 Tokachi-Oki (Mw8.3) and 2005 Miyagi-Oki (Mw7.2) earthquakes, which were also elongate in the slip direction (Koketsu et al 2004;Yaginuma et al 2007;Wu et al 2008).…”

Section: Elongate Slip Distributionmentioning

confidence: 83%

Streak and hierarchical structures of the Tohoku–Hokkaido subduction zone plate boundary

Okuda

Ide

2018

Earth Planets Space

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Here, we investigated four families of moderate-size (M ~ 4.8) repeating earthquakes and nearby smaller events that occurred in the Naka-Oki, Kushiro-Oki, Urakawa-Oki, and Kamaishi-Oki regions of the Tohoku-Hokkaido subduction zone, Japan, between 2002 and 2017. We employed a hypocenter relocation method based on waveform crosscorrelations of the above four families, as well as a waveform inversion method using the empirical Green's function for the Naka-Oki and Kushiro-Oki earthquakes, where every moderate-size repeating earthquake showed complex and variable rupture processes. However, their rupture areas overlapped significantly and were elongate parallel to the slip direction. Some parts of these areas were also repeatedly ruptured by smaller earthquakes, with these smaller earthquakes and moderate events sometimes following almost identical rupture processes. The results indicate the existence of a characteristic structure that is represented by several elliptical patches that are elongate in the slip direction of the plate interface. It is likely that many streak structures have developed over a 1000 km along-strike section of the plate interface that extends from the Kushiro-Oki region to the Naka-Oki region of the subduction zone. These patches may be distributed hierarchically, with the smaller patches rupturing independently. The rupture of a smaller patch may either stop, producing a small earthquake, or it may grow into a large earthquake, with this rupture process depending on subtle differences in the physical conditions that we are unable to observe in a practical sense. Earthquakes are random processes, but they may not be completely random, as the preexisting characteristic structure of the seismic region may control the rupture process to some degree.

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Section: Elongate Slip Distributionmentioning

confidence: 83%

Streak and hierarchical structures of the Tohoku–Hokkaido subduction zone plate boundary

Okuda

Ide

2018

Earth Planets Space

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“…We identified two asperities in the 2005 earthquake that are close to the two southern asperities of the 1978 earthquake, although Okada et al [2005] and Yaginuma et al [2007] recovered a single asperity around the hypocenter based on their waveform inversions of the 2005 earthquakes. The existence of two asperities is supported directly by the observed strong motion waveforms, which clearly indicate two seismic pulses (A and B in Figure 10).…”

Section: Discussionmentioning

confidence: 96%

Source processes of the 1978 and 2005 Miyagi‐oki, Japan, earthquakes: Repeated rupture of asperities over successive large earthquakes

Koketsu

Miyake

2008

J. Geophys. Res.

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[1] Highly similar seismograms commonly observed along transform or convergent plate boundaries indicate that repeated small to moderate earthquakes occur within a single area. The results of source-process inversions for seismic events within the northeastern Japan subduction zone suggest that large earthquakes and their component asperities also exhibit this repeating nature under certain conditions. However, sets of similar seismograms that might provide direct evidence of the repeated rupture of large-earthquake asperities have not been observed. This paper analyzes two offshore earthquakes near Miyagi Prefecture, Japan, the most recent occurring

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“… Wu et al [2008] obtained results similar to that of Yamanaka and Kikuchi [2004]. In the case of the 2005 event, Wu et al [2008] recovered two asperities although Okada et al [2005] and Yaginuma et al [2007] indicated a single asperity around the hypocenter. As mentioned by Wu et al [2008], two distinct pulses in the strong motion data support the existence of two asperities during the 2005 event.…”

Section: Dynamic Source Modelingmentioning

confidence: 64%

“…According to the kinematic models of Wu et al [2008], asperity C was ruptured during the 2005 event. However, Okada et al [2005] and Yaginuma et al [2007] showed kinematic models without the rupture in asperity C as mentioned in section 2. Therefore we cannot discuss on the difference of the fracture energy in the same asperity when we refer their source models.…”

Section: Comparison Of Source Parameters Between Models M78 and M05mentioning

confidence: 96%

“…Historical records reveal that large offshore earthquakes with magnitudes of about 7.5 and recurrence interval of approximately 37.1 years have occurred repeatedly in the Miyagi‐oki region, as shown in Figure 1 [ Earthquake Research Committee , 2005]. For the most recent two events that occurred in 1978 and 2005, several kinematic source models were proposed [ Yamanaka and Kikuchi , 2004; Okada et al , 2005; Yaginuma et al , 2007; Wu et al , 2008]. Previous studies reported that both events occurred on the plate boundary, and also that the large northern asperity (area exhibiting large slip) that ruptured during the 1978 event ( M w 7.6) did not rupture during the 2005 event ( M w 7.2).…”

Section: Introductionmentioning

confidence: 99%

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Dynamic source modeling of the 1978 and 2005 Miyagi‐oki earthquakes: Interpretation of fracture energy

Kimura¹,

Koketsu²,

Wu³

et al. 2010

J. Geophys. Res.

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[1] We constructed spontaneous dynamic rupture models of the 1978 and 2005 Miyagi-oki, Japan, earthquakes, which occurred on the same plate boundary repeatedly with different magnitudes, to reproduce the slip and the rupture velocity predicted by kinematic source models. Comparison of the dynamic source parameters of these events enables us to consider the behavior of rupture dynamics during different source processes on the same fault. In particular, we compared the stress drop and the fracture energy, which can be evaluated stably, between two events. The maximum and average values of the stress drop over the whole fault plane and on an asperity that ruptured during both events are almost identical in the two models. On the other hand, the 1978 event, whose magnitude was larger than the 2005 event, has a fracture energy value larger than that of the 2005 event not only over the whole fault but also on the asperity that ruptured repeatedly. These results are consistent with previous studies of the scaling of fracture energy with the seismic moment. We also compared the fracture energy values with those of other inland events estimated for previous studies; our values for the Miyagi-oki earthquakes are smaller. Differences in tectonic setting between shallow inland events and deep subduction-zone events might cause this discrepancy.

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Coseismic Slip Distribution of the 2005 Miyagi-Oki (M 7.2) Earthquake Estimated by Inversion of Strong-motion and Teleseismic Waveforms

Cited by 6 publications

References 11 publications

Streak and hierarchical structures of the Tohoku–Hokkaido subduction zone plate boundary

Streak and hierarchical structures of the Tohoku–Hokkaido subduction zone plate boundary

Source processes of the 1978 and 2005 Miyagi‐oki, Japan, earthquakes: Repeated rupture of asperities over successive large earthquakes

Dynamic source modeling of the 1978 and 2005 Miyagi‐oki earthquakes: Interpretation of fracture energy

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