Splay Fault Branching Along the Nankai Subduction Zone

Park, Jin-Oh; Tsuru, Takeshi Go; Kodaira, Shuichi; Cummins, Phil R.; Kaneda, Yasufumi

doi:10.1126/science.1074111

Cited by 555 publications

(616 citation statements)

References 19 publications

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“…• It is geographically coincident with the updip termination of slip during the 1944 Tonankai event, as inferred from tsunami (Tanioka and Satake, 2001) and seismic (Kikuchi et al, 2003) waveform inversions, and recent structural studies indicate that it may have experienced coseismic slip (e.g., Park et al, 2002).…”

Section: Background Geological Settingmentioning

confidence: 89%

“…A significant, laterally extensive fault system (the "megasplay" fault; Park et al, 2002) slips in discrete events that may include tsunamigenic slip during great earthquakes. During the interseismic period, the megasplay remains locked and accumulates strain.…”

Section: Overview Of the Nantroseize Complex Drilling Projectmentioning

confidence: 99%

“…At Nankai Trough, high-resolution images of the outer rise from seismic reflection profiles clearly document a large out-of-sequence thrust (OOST) fault system (the megasplay fault after Park et al, 2002) that branches from the plate boundary décollem-ent within the coseismic rupture zone of the 1944 Tonankai M 8.2 earthquake (Fig. F2).…”

Section: Overview Of the Nantroseize Complex Drilling Projectmentioning

confidence: 99%

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Kimura¹,

Screaton²,

Curewitz³

et al. 2008

IODP Preliminary Report

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Section: Background Geological Settingmentioning

confidence: 89%

Section: Overview Of the Nantroseize Complex Drilling Projectmentioning

confidence: 99%

Section: Overview Of the Nantroseize Complex Drilling Projectmentioning

confidence: 99%

See 1 more Smart Citation

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Kimura¹,

Screaton²,

Curewitz³

et al. 2008

IODP Preliminary Report

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“…Combining swath-bathymetry and seismic reflection data has demonstrated a causal relationship between splay-fault behavior and seafloor lineament topography in segment C, i.e., the 1944 Tonankai earthquake rupture area (Park et al, 2002). Many 2-D and 3-D seismic re ection data (Park et al, 2003(Park et al, , 2010Moore et al, 2007) have revealed a steeply landward-dipping splay-fault system in segment C, e.g., line 4 in Fig.…”

Section: Swath-bathymetry Data and Their Interpretationmentioning

confidence: 98%

“…In particular, the Nankai subduction zone off Kii Peninsula (Fig. 1) is characterized by steeply landward-dipping megasplay faults (Park et al, 2002;Moore et al, 2007) in the rupture area of the 1944 Tonankai (M 8.1) earthquake. This megasplay fault branches upward from the plate interface (i.e., the megathrust fault), breaking through the overlying accretionary wedge.…”

Section: Introductionmentioning

confidence: 99%

Seismic reflection and bathymetric evidences for the Nankai earthquake rupture across a stable segment-boundary

Park

Kodaira

2012

Earth Planet Sp

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Seismic re ection pro les reveal steeply landward-dipping splay faults in segment B (the 1946 Nankai earthquake rupture, M 8.3) as well as segment C (the 1944 Tonankai earthquake rupture, M 8.1) of the Nankai subduction zone. The splay faults, branching upward from the plate-boundary interface, almost reach the sea oor, producing sea oor fault scarps. The swath-bathymetry map exhibits a ∼200-km-long, remarkable sea oor lineament with which the sea oor fault scarps align in the segments B and C. The sea oor lineament, which we believe is produced by repeating slips on the splay faults, is almost laterally continuous across a stable boundary off Kii Peninsula inbetween the two segments. These sea oor and subsurface features could be due to multiple, simultaneous coseismic slips across the B-C boundary, when subduction thrust earthquakes accompany the coseismic slips on the splay fault. The splay faults are associated with (1) uid expulsion, (2) dynamic deformation, and (3) tsunami generation.

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Contrasts in physical properties between the hanging wall and footwall of an exhumed seismogenic megasplay fault in a subduction zone—An example from the Nobeoka Thrust Drilling Project

Hamahashi

Saito

Kimura

et al. 2013

Geochem Geophys Geosyst

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[1] We examined the physical properties of an exhumed and fossilized subduction zone megasplay fault by analyzing geophysical logging data obtained by the Nobeoka Thrust Drilling Project, which provide a high-resolution transect of properties across the main fault zone. The footwall cataclasite exhibits higher averages of neutron porosity (7.6%) and lower values of electric resistivity (232 Xm) compared to the hanging wall phyllite (4.8%, 453 Xm). This clear contrast between the hanging wall and footwall may account for the difference in maximum burial and structural variation. Despite the contrast observed between the hanging wall and footwall in macroscopic scale, the resistivity and porosity data from both the hanging wall and footwall can be fit with a single curve using Archie's law, suggesting the similarities in microstructures and mineralogy in this low porosity range. Above the main fault core of the Nobeoka Thrust a brittle damage zone in the hanging wall contains pseudotachylyte as evidence of the seismogenic slip and does not follow Archie's law. Damage zones in the hanging wall are also observed in the modern splay fault at shallow depth in the Nankai Trough but with much thicker width, whereas the footwall damage zone is more extensive in the Nobeoka Thrust. Splay faults may exhibit strong deformation in the hanging wall in the early stage, and as fault rocks get buried deeper and as displacement and physical property contrast increase across the fault, the damage effect may eventually be enlarged in the footwall.

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Splay Fault Branching Along the Nankai Subduction Zone

Cited by 555 publications

References 19 publications

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Untitled

Seismic reflection and bathymetric evidences for the Nankai earthquake rupture across a stable segment-boundary

Contrasts in physical properties between the hanging wall and footwall of an exhumed seismogenic megasplay fault in a subduction zone—An example from the Nobeoka Thrust Drilling Project

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