Aftershock observation of the 2003 Tokachi-oki earthquake by using dense ocean bottom seismometer network

Shinohara, Masanao; Yamada, Tomoaki; Kanazawa, Toshihiko; Hirata, Naoshi; Kaneda, Yasufumi; Takanami, Tetsuo; Mikada, H.; Suyehiro, Kiyoshi; Sakai, Shin’ichi; Watanabe, Tomoki; Uehira, Kenji; Murai, Yoshio; Takahashi, Narumi; Nishino, Minoru; Mochizuki, Kimihiro; Sato, Takeshi; Araki, Eiichiro; Hino, Ryota; Uhira, K.; Shiobara, Hajime; Shimizu, Hiroshi

doi:10.1186/bf03353054

Cited by 28 publications

(22 citation statements)

References 10 publications

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“…6(d)). Such a temporal evolution of the afterslip is consistent with the distribution of aftershocks that mainly occurred in a peripheral area of the coseismic slip region (Shinohara et al, 2004;Ito et al, 2004). In particular, the northeastward propagation of the aftershock distribution is in good agreement with the afterslip migration in Fig.…”

Section: Resultssupporting

confidence: 57%

Coseismic and postseismic crustal deformation after the M w 8 Tokachi-oki earthquake in Japan

et al. 2014

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The permanent Global Positioning System (GPS) array in Japan detected coseismic and postseimic deformation of the 2003 Tokachi-oki earthquake (M w 8). We estimate the time evolution of its postseismic slip, together with its coseismic slip distribution. The result shows that the postseismic slip has been occurring mainly in an area adjacent to the coseismic slips, propagating to the northeast and southwest. This suggests that, as of March 6, 2004, the postseismic slip of the strongly coupled area neighboring the coseismic rupture partly released seismic moment, equivalent to an earthquake of M w 7.8.

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Section: Resultssupporting

confidence: 57%

Coseismic and postseismic crustal deformation after the M w 8 Tokachi-oki earthquake in Japan

et al. 2014

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“…The precise determination of aftershock distribution, however, is difficult using only land seismic network data when the source region is widely spread under an offshore area near a coast line. It is widely known that an ocean bottom seismometer (OBS) observation is essential to obtain a high-resolution aftershock distribution associated with large earthquakes that occur in the marine environment (e.g., Shinohara et al, 2004Shinohara et al, , 2008Sakai et al, 2005;Hino et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Aftershock observation of the 2011 off the Pacific coast of Tohoku Earthquake by using ocean bottom seismometer network

et al. 2011

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The 2011 off the Pacific coast of Tohoku Earthquake occurred offshore of northeast Japan region on March 11th, 2011. In order to study the aftershock activity of this event, we started deployment of seventy-two ocean bottom seismometers (OBSs) four days after the mainshock. In the south of the source region, thirty-four longterm OBSs (LT-OBSs) had been deployed before the occurrence of the mainshock, and we recovered three LTOBSs to clarify the depth distribution of aftershocks. Using the data of OBSs, ninety-nine aftershocks were located. Most of the aftershocks were located in a depth range of 5-30 km and concentrate in the plate boundary region. In addition, aftershocks occurred within the subducting oceanic crust and the 6.2-km/s layer of the landward plate. No aftershocks were found in the mantle of the subducting plate. From the results of a previous seismic survey using OBSs and controlled sources, the subducting Philippine Sea plate is estimated to be in contact with the subducting Pacific plate. The southern end of the seismic activity region of the aftershocks corresponds to the contact region of two subducting plates. We infer that the rupture of the mainshock sequence was terminated at the oceanic plate contact region.

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“…The precise determination of aftershock distribution is difficult using only land seismic network data when the source region is positioned under an offshore area near a coast line. It is widely known that an ocean bottom seismometer (OBS) observation is essential to obtain a high-resolution aftershock distribution associated with large earthquakes that occurred in the marine environment (e.g., Shinohara et al, 2004;Sakai et al, 2005;Yamada et al, 2005). In addition, a spatially dense OBS observation is also necessary for a precise distribution of aftershocks occurring near a coast line be- cause a seismic network must cover a whole source region (Uehira et al, 2006;Yamada et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Precise aftershock distribution of the 2007 Chuetsu-oki Earthquake obtained by using an ocean bottom seismometer network

et al. 2008

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The Chuetsu-Oki Earthquake occurred on July 16, 2007. To understand the mechanism of earthquake generation, it is important to obtain a detailed seismic activity. Since the source region of the 2007 Chuetsu-oki Earthquake lies mainly offshore of Chuetsu region, a central part of Niigata Prefecture, it is difficult to estimate the geometry of faults using only the land seismic network data. A precise aftershock distribution is essential to determine the fault geometry of the mainshock. To obtain the detailed aftershock distribution of the 2007 Chuetsu-oki Earthquake, 32 Ocean Bottom Seismometers (OBSs) were deployed from July 25 to August 28 in and around the source region of the mainshock. In addition, a seismic survey using airguns and OBSs was carried out during the observation to obtain a seismic velocity structure below the observation area for precise hypocenter determination. Seven hundred and four aftershocks were recorded with high spatial resolution during the observation period using OBSs, temporally installed land seismic stations, and telemetered seismic land stations and were located using the double-difference method. Most of the aftershocks occurred in a depth range of 6-15 km, which corresponds to the 6-km/s layer. From the depth distribution of the hypocenters, the aftershocks occurred along a plane dipping to the southeast in the whole aftershock region. The dip angle of this plane is approximately 40• . This single plane with a dip to the southeast is considered to represent the fault plane of the mainshock. The regions where few aftershocks occurred are related to the asperities where large slip is estimated from the data of the mainshock. The OBS observation is indispensable to determine the precise depths of events which occur in offshore regions even close to a coast.

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Aftershock observation of the 2003 Tokachi-oki earthquake by using dense ocean bottom seismometer network

Cited by 28 publications

References 10 publications

Coseismic and postseismic crustal deformation after the M w 8 Tokachi-oki earthquake in Japan

Coseismic and postseismic crustal deformation after the M w 8 Tokachi-oki earthquake in Japan

Aftershock observation of the 2011 off the Pacific coast of Tohoku Earthquake by using ocean bottom seismometer network

Precise aftershock distribution of the 2007 Chuetsu-oki Earthquake obtained by using an ocean bottom seismometer network

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