Episodic seafloor mud brecciation due to great subduction zone earthquakes

Sakaguchi, Arito; Kimura, Gaku; Strasser, Michael; Screaton, E.; Curewitz, D.; Murayama, Masafumi

doi:10.1130/g32043.1

Cited by 46 publications

(27 citation statements)

References 30 publications

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“…To better understand the seismogenic zone, the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) of the Integrated Ocean Drilling Program (IODP) targeted this mega-splay fault (e.g., Tobin and Kinoshita 2006;Kinoshita et al 2009). Mud-breccia units were observed in the drilled cores from the hanging wall of the mega-splay fault, and the shallowest of these was attributed to strong ground shaking during the 1944 Tonankai earthquake (Sakaguchi et al 2011). Historical and archeological records have documented recurring great earthquakes along the Nankai Trough (Ando 1975).…”

Section: Geological and Geophysical Backgroundmentioning

confidence: 99%

Accumulation of an earthquake-induced extremely turbid layer in a terminal basin of the Nankai accretionary prism

et al. 2014

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Seismic shaking is a major trigger for sediment redistribution in subduction zones, and clouds of dilute suspended sediment have been reported in association with large earthquakes. Dive observations in a basin on the slope of the central Nankai accretionary prism soon after the 2004 off-Kii Peninsula earthquakes documented a layer of suspended sediment with extremely high turbidity. We estimated the thickness of this bottom turbid layer to be more than 2.5 m by comparison of seafloor depths between surveys in 2004 and 2010 and about 2.6 m from instrumental evidence involving the submersion of a heat-flow probe. A high-resolution subbottom profiling survey across the basin revealed acoustically transparent layers thicker than 2 m. Because the slope basin is a terminal basin completely enclosed by topographic highs, we examined the possibility that the uppermost transparent layer was deposited as a consequence of the 2004 earthquakes. Considering the sediment source area and the volume of the basin fills, the mobilization and redeposition of thin surface sediments on the prism slope can account for the volume of the transparent layer. We conclude that the 2004 earthquakes caused widespread disturbance of the prism slope and concentrated surface sediments in this terminal basin. Our results emphasize the utility of a terminal basin in a subduction zone as an earthquake recorder.

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Section: Geological and Geophysical Backgroundmentioning

confidence: 99%

Accumulation of an earthquake-induced extremely turbid layer in a terminal basin of the Nankai accretionary prism

et al. 2014

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“…4b). Geological records are sparse for both earthquakes, however shaking in 1944 may be recorded in turbidite and mud-breccia records from the Kumano Trough (Sakaguchi et al, 2011;Shirai et al, 2010) and in liquefaction deposits at Tadokoro (Sangawa, 2009). Archaeological sites on the western side of the Kii Peninsula and in eastern Shikoku may record liquefaction resulting from the 1946 earthquake (Sangawa, 2009).…”

Section: Rupture Zones Of Historical Earthquakesmentioning

confidence: 99%

“…yr BP, while the fourth and fifth units predate 10580 -10670 cal. yr BP (Sakaguchi et al, 2011). The presence of brecciated units on the hanging-wall slope of a megasplay fault but absence on the footwall slope suggests slip on the megasplay and stronger ground motion above the hanging wall (resulting from the significant upward motion) are required to generate mud-breccia units at ODP site C0004.…”

Section: The Western Tōnankai (C) Segmentmentioning

confidence: 99%

A systematic review of geological evidence for Holocene earthquakes and tsunamis along the Nankai-Suruga Trough, Japan

Garrett

Fujiwara

Garrett

et al. 2016

Earth-Science Reviews

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. ABSTRACTThe Nankai-Suruga Trough, the subduction zone that lies immediately south of Japan's densely populated southern coastline, generates devastating great earthquakes (magnitude > 8) characterised by intense shaking, crustal deformation and tsunami generation. Forecasting the hazards associated with future earthquakes along this >700 km long fault requires a comprehensive understanding of past fault behaviour. While the region benefits from a long and detailed historical record, palaeoseismology has the potential to provide a longer-term perspective and additional crucial insights. In this paper, we summarise the current state of knowledge regarding geological evidence for past earthquakes and tsunamis along the Nankai-Suruga Trough. Incorporating literature originally published in both Japanese and English and enhancing available results with new age modelling approaches, we summarise and critically evaluate evidence from a wide variety of sources. Palaeoseismic evidence includes uplifted marine terraces and biota, marine and lacustrine turbidites, liquefaction features, subsided marshes and tsunami deposits in coastal lakes and lowlands. While 75 publications describe proposed evidence from more than 70 sites, only a limited number provide compelling, well-dated evidence. The best available records enable us to map the most likely rupture zones of twelve earthquakes that occurred during the historical period. This spatiotemporal compilation suggests that the AD 1707 earthquake ruptured almost the full length of the subduction zone and that earthquakes in AD 1361 and 684 may have been predecessors of similar magnitude. Intervening earthquakes were of lesser magnitude, highlighting the variability in rupture mode that characterises the Nankai-Suruga Trough. Intervals between ruptures of the same seismic segment range from less than 100 to more than 450 years during the historical period. Over longer timescales, palaeoseismic evidence suggests intervals between earthquakes ranging from 100 to 700 years, however these figures reflect a range of thresholds controlling the creation and preservation of evidence at any given site as well as the genuine intervals between earthquakes. At present, there is no geological data that suggest the occurrence of a larger magnitude earthquake than that experienced in AD 1707, however few studies have sought to establish the relative magnitudes of different earthquake and tsunami events along the Nankai-Suruga Trough. Alongside the lack of...

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“…The Nankai Trough subduction zone has been the site of recurring, typically tsunamigenic great earthquakes larger than M w > 8.0, including the 1944 Tonankai M w 8.2 and 1946 Nankai M w 8.3 earthquakes (Ando 1975;Hori et al 2004). Recent tsunami and seismic waveform inversions, seismic reflection studies, and mud breccia analyses suggest that the coseismic slip during the 1944 Tonankai earthquake occurred along the megasplay fault (Tanioka and Satake 2001;Park et al 2002;Kikuchi et al 2003;Sakaguchi et al 2011;Park and Kodaira 2012). In addition, slow slip events or very low frequency earthquakes have recently been found to occur not only within the accretionary prism, but also along the décolle-ment between the outer ridge and the deformation front (Ito and Obara 2006;Sugioka et al 2012).…”

Section: Geologic Settingmentioning

confidence: 99%

Frictional properties of the shallow Nankai Trough accretionary sediments dependent on the content of clay minerals

et al. 2014

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We conducted triaxial friction experiments on the shallow Nankai Trough accretionary sediments at confining pressures, pore water pressures, temperatures close to their in situ conditions, and axial displacement rates (V axial ) changed stepwise among 0.1, 1, and 10 μm/s. The results revealed that their frictional properties change systematically according to the content of clay minerals, smectite in particular. The steady-state friction coefficient (μ ss ) at V axial = 1 μm/s decreases with increasing clay mineral content, shown in weight percent, from 0.82 for a sandstone sample (6 wt%), through 0.71 for a tuff sample (≈17 wt%), and 0.53 to 0.56 for siltstone samples (29 to 34 wt%), to 0.25 for a claystone sample (42 wt%). Slip-dependent frictional behavior changes accordingly from slip hardening for the sandstone sample, through quasi steady-state slip for the tuff and siltstone samples, to distinct slip weakening for the claystone sample. Although all samples exhibit velocity-strengthening behavior upon stepwise changes in sliding velocity, the ratio of the (a − b) value to the velocity dependence of steady-state friction (Δμ ss /ΔlnV sliding ) decreases with increasing clay mineral content, which implies that the friction component decreases while the flow component increases accordingly. Thus, faulting in the shallow Nankai Trough accretionary prism is likely controlled by the clay mineral content, in particular the smectite content, in the sediments as well as in the fault zones.

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Episodic seafloor mud brecciation due to great subduction zone earthquakes

Cited by 46 publications

References 30 publications

Accumulation of an earthquake-induced extremely turbid layer in a terminal basin of the Nankai accretionary prism

Accumulation of an earthquake-induced extremely turbid layer in a terminal basin of the Nankai accretionary prism

A systematic review of geological evidence for Holocene earthquakes and tsunamis along the Nankai-Suruga Trough, Japan

Frictional properties of the shallow Nankai Trough accretionary sediments dependent on the content of clay minerals

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