A unified source model for the 2011 Tohoku earthquake

Koketsu, Kazuki; Yokota, Yusuke; Nishimura, Naoki; Yagi, Y.; Miyazaki, S.; Satake, Kenji; Fujii, Y.; Miyake, Hideaki; Sakai, Shin’ichi; Yamanaka, Yasuhiro; Okada, Tomomi

doi:10.1016/j.epsl.2011.09.009

Cited by 247 publications

(202 citation statements)

References 23 publications

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“…Several seismological, geodetic, and tsunami wave inversion studies indicate a large magnitude of coseismic slip (30-60 m) occurred on the shallow portions of the plate boundary [e.g., Ide et al, 2011;Yokota et al, 2011;Fujii et al, 2011;Koketsu et al, 2011]. Differential bathymetric and seafloor geodetic studies [Fujiwara et al, 2011;Sato et al, 2011;Ito et al, 2011] also document large coseismic displacement near the trench.…”

Section: Introductionmentioning

confidence: 99%

High‐resolution seismic imaging in the Japan Trench axis area off Miyagi, northeastern Japan

Nakamura

Kodaira

Miura

et al. 2013

Geophysical Research Letters

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Newly obtained high‐resolution seismic data reveal the detailed structure of the Japan Trench axis off Miyagi, Japan, in the region of large shallow slip during the 11 March 2011 M9 Tohoku earthquake. Correlation of seismic images with previous drilling results identifies a possible basal chert‐rich layer and hemipelagic/pelagic mudstones overlying igneous Pacific crust. Mapping of acoustic basement depicts the subduction of horst‐and‐graben topography. The basement and basal chert are subducted beneath a seismically chaotic frontal prism, but the majority of overlying hemipelagic mudstones is offscraped and imbricated at the trench axis as a result of plate boundary compression. A possible décollement is imaged as a seaward dipping reflection at landward part of the trench graben and was likely generated by loading and failure of underthrust sediments. Collectively, these analyses provide a structural framework for understanding sedimentary inputs and the localization of shallow plate boundary slip at the Japan Trench.

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Section: Introductionmentioning

confidence: 99%

High‐resolution seismic imaging in the Japan Trench axis area off Miyagi, northeastern Japan

Nakamura

Kodaira

Miura

et al. 2013

Geophysical Research Letters

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“…Seismic segments in ADDS are, on the other hand, rather wide. The 2011 Tohoku-oki megathrust earthquake revealed that the strongly-coupled segments exist in the trench-ward of ADDS, where the millennial seismic-asperity of the event was observed [16,17]. This is also true in the 1964 Alaska earthquake [18], showing a very strong asperity in the Alaska Bay close to the Aleutian Trench.…”

Section: Diversity Of Megathrust Earthquakes In the Worldmentioning

confidence: 48%

Tsunamigenic Earthquakes at Along-dip Double Segmentation and Along-strike Single Segmentation near Japan

Koyama

Tsuzuki

Yomogida

2015

JMSE

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A distinct difference of the earthquake activity in megathrust subduction zones is pointed out, concerning seismic segmentations in the vicinity of Japan-that is, the apparent distribution of earthquake hypocenters characterized by Along-dip Double Segmentation (ADDS) and Along-strike Single Segmentation (ASSS). ADDS is double aligned seismic-segmentation of trench-ward seismic segments along the Japan Trench and island-ward seismic segments along the Pacific coast of the Japan Islands. The 2011 Tohoku-oki megathrust earthquake of Mw9.0 occurred in ADDS. In the meantime, the subduction zone along the Nankai Trough, the western part of Japan, is the source region of a multiple rupture of seismic segments by the 1707 Houei earthquake, the greatest earthquake in the history of Japan. This subduction zone is narrow under the Japan Islands, which is composed of single aligned seismic-segmentation side by side along the Nankai Trough, which is typical of ASSS. Looking at the world seismicity, the 1960 and 2010 Chile megathrusts, for example, occurred in ASSS, whereas the 1952 Kamchatka and the 1964 Alaska megathrusts occurred in ADDS. These megathrusts in ADDS result from the rupture of strong asperity in the trench-ward seismic segments. Since the asperity of earthquakes in OPEN ACCESSJ. Mar. Sci. Eng. 2015, 3 1179 ASSS is concentrated in the shallow part of subduction zones and the asperity of frequent earthquakes in ADDS is in deeper parts of the island-ward seismic segments than those of ASSS, there must be a difference in tsunami excitations due to earthquakes in ADDS and ASSS. An analysis was made in detail of tsunami and seismic excitations of earthquakes in the vicinity of Japan. Tsunami heights of ASSS earthquakes are about two times larger than those of ADDS earthquakes with the same value of seismic moment. The reason for this different tsunami excitation is also considered in relation to the seismic segmentations of ADDS and ASSS.

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“…(e.g., Fujii et al, 2011;Ide et al, 2011;Ito et al, 2011a;Koketsu et al, 2011;Iinuma et al, 2012a). A strike-normal slip distribution became the focus of the discussion, and it was seafloor geodetic data that led to the final conclusion that quite a large slip had occurred in the shallow part of the plate boundary near the trench.…”

Section: Some Important Results Of Gpsa Observations Before 2011mentioning

confidence: 99%

Seafloor Geodetic Approaches to Subduction Thrust Earthquakes

Fujimoto¹

2014

Monogr. Environ. Earth Planets

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Observation systems and some observed results of seafloor geodesy are reviewed with a focus on the research activities of Japanese groups, especially those of Tohoku University. Seafloor acoustic ranging has been adopted as the simplest way to continuously monitor local crustal activities. The GPS-Acoustic (GPSA) method has been the most important for seafloor positioning. It seems that commercial technologies can be used to lessen the considerable differences in repeatability and spatio-temporal resolution of GPSA and land based GPS. Ocean bottom pressure sensors have been used to continuously monitor vertical crustal movements. Improvements in the resolution and long-term stability of pressure sensors will lead to monitoring slow slip events and interplate locking. Ocean bottom and underwater gravimeters have been developed for precise gravity mapping and monitoring mass change beneath the seafloor. The 2011 Tohoku-oki earthquake is an historical event demonstrating that seafloor geodetic observations are crucial to understanding the mechanism of giant earthquakes. Coseismic displacements detected through geodetic observations on the seafloor have indicated huge slips on the shallow part of the plate boundary. A slow slip event near the zone of the coseismic slip preceding the main event has been detected from slight pressure variations. This illustrates the importance of real-time monitoring with a cabled seafloor observatory, which is also a key to establishing a reliable early tsunami warning system.

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A unified source model for the 2011 Tohoku earthquake

Cited by 247 publications

References 23 publications

High‐resolution seismic imaging in the Japan Trench axis area off Miyagi, northeastern Japan

High‐resolution seismic imaging in the Japan Trench axis area off Miyagi, northeastern Japan

Tsunamigenic Earthquakes at Along-dip Double Segmentation and Along-strike Single Segmentation near Japan

Seafloor Geodetic Approaches to Subduction Thrust Earthquakes

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