Seismic velocity, anisotropy, and fluid pressure in the Barbados accretionary wedge from an offset vertical seismic profile with seabed sources

Hayward, N; Westbrook, G. K.; Peacock, Sheila

doi:10.1029/2001jb001638

Cited by 16 publications

(19 citation statements)

References 45 publications

(76 reference statements)

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“…In undeformed sedimentary basin, the vertical effective stress s Moore and Tobin, 1997;Hayward et al, 2003;McNeill et al, 2004]. Although the maximum principal stress direction may be changed seaward of the deformation front and the horizontal stress becomes the maximum principal stress within accretionary prism, we cannot determine the stress characteristics around the deformation front from seismic interval velocity.…”

Section: Effective Stressmentioning

confidence: 99%

“…Because we cannot estimate stress anisotropy from isotropic seismic velocities, we use the estimated mean effective stress for pressure prediction in this study. If we quantitatively consider stress state (principal stress direction) from seismic data, we should use velocity anisotropy and introduce anisotropic media (crack orientation) [e.g., Hudson, 1981;Crampin, 1985;Jakobsen et al, 2000;Peacock, 2003;Hayward et al, 2003].…”

Section: Effective Stressmentioning

confidence: 99%

“…These studies using seismic data have focused mainly on the décollement reflection only in order to reveal its characteristics including pore pressure, although some studies have used seismic velocity data to predict pore pressure distributions within some accretionary wedges: the Nankai accretionary prism [Tobin and Saffer, 2003], the Barbados accretionary prism [Westbrook, 1991;Hayward et al, 2003], and the Oregon accretionary prism [Cochrane et al, 1994].…”

Section: Introductionmentioning

confidence: 99%

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Effective stress and pore pressure in the Nankai accretionary prism off the Muroto Peninsula, southwestern Japan

Tsuji¹,

Tokuyama²,

Pisani³

et al. 2008

J. Geophys. Res.

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[1] We developed a theoretical method for predicting effective stress and pore pressure based on rock physics model. We applied the method to reveal the pore pressure distribution within the Nankai accretionary prism off southwestern Japan and to investigate variations in pore pressure associated with evolution of the plate boundary décollement. From the crack aspect ratio spectrum estimated from laboratory and well-log data, we calculated a theoretical relationship between acoustic velocity and mean effective stress by using differential effective medium theory. By iteratively fitting the theoretically calculated velocity to the seismic velocities derived from 3D tomographic inversion, we estimated in situ mean effective stress within the accretionary prism. Pore pressure is then the difference between the effective stress and the confining stress. When we calculated pore pressure, we considered compressive state of stress in the accretionary prism. Our results confirm that pore fluid pressure is high within the subducting sedimentary sequence below the décollement; we determined a normalized pore pressure ratio (l*) of 0.4-0.7. Abnormal pore pressures develop in the underthrust sequence as a result of the increase in overburden load because of the thickened overlying prism and a low permeability barrier across the décollement. Overpressuring within the accreted sequence is initiated at the deformation front and proceeds landward. The increase in horizontal compaction within the accreted sequence may raise pore pressures within the accreted sequence, and the pore pressure (mean effective stress) contrast at the décollement becomes smaller landward of the deformation front.Citation: Tsuji, T., H. Tokuyama, P. Costa Pisani, and G. Moore (2008), Effective stress and pore pressure in the Nankai accretionary prism off the Muroto Peninsula, southwestern Japan,

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Section: Effective Stressmentioning

confidence: 99%

Section: Effective Stressmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effective stress and pore pressure in the Nankai accretionary prism off the Muroto Peninsula, southwestern Japan

Tsuji¹,

Tokuyama²,

Pisani³

et al. 2008

J. Geophys. Res.

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“…[21] Also as concerns the fluid pressure ratio within the basal shear zone, l b , a comparison with other accretionary wedges shows it is commonly greater than l within the wedge [e.g., Saffer andBekins, 2002, 2006;Hayward et al, 2003]. According to numerical modeling and for the sake of simplicity, in our calculations we tested the l b varying from 0 to 50% greater than l. Figure 5.…”

Section: Pore Fluid Pressurementioning

confidence: 99%

The sub‐Himalayan fold‐thrust belt in the 1905 Kangra earthquake zone: A critical taper model perspective for seismic hazard analysis

2012

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[1] We investigate the broader epicentral area of the M = 7.8, 1905 Kangra earthquake(s), north India, affecting the sub-Himalayan hills. The tectonics of the area is characterized by two major rentrants (Kangra and Dehradun) interposed by the Nahan Salient. The first-order topography between the Himalayan Frontal Thrust and the Main Boundary Thrust shows a marked lateral variation along strike of the mean gradient, characterized by a very small mean slope angle ($1 ) in correspondence with the reentrants and higher values ($3 ) in the salient. These tectonic and topographic features also show a good correspondence with the peculiar macroseismic field of the 1905 event(s), which is characterized by two distinct intensity maxima, separated by a distance of $150 km, clearly overlapping the two major tectonic reentrants. In this paper, based on available geological and geophysical information and a critical analysis of the general mechanical constraints, the seismogenic volume of the external sector of the chain is investigated in terms of critical taper model attempting to clarify the possible correlations between tectonics, topography and seismicity in the sub-Himalayan belt. Based on different assumptions, three possible seismotectonic scenarios are explored in order to constrain their likelihood and therefore to suggest a potential seismic gap in the area corresponding to the Nahan Salient, which may experience an event of significant magnitude in the future.

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“…These have included the Barbados accretionary prism [128][129][130], Central and South America [131], the South Sandwich Arc [93,132,133], the Mediterranean Ridge [134], an accretionary prism west of the Gibraltar Straits [135], Japan [136][137][138], Indonesia [139,140] and Timor [141]. The changing physiography associated with development of subduction zones can significantly affect ocean circulation and thus climate [142].…”

Section: (B) Volcanic Islandsmentioning

confidence: 99%

Aspects of marine geoscience: a review and thoughts on potential for observing active processes and progress through collaboration between the ocean sciences

Mitchell

2012

Phil. Trans. R. Soc. A.

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Much progress has been made in the UK in characterizing the internal structures of major physiographic features in the oceans and in developing understanding of the geological processes that have created or shaped them. UK researchers have authored articles of high impact in all areas described here. In contrast to terrestrial geoscience, however, there have been few instrumented observations made of active processes by UK scientists. This is an area that could be developed over the next decades in the UK. Research on active processes has the potential ability to engage the wider public: Some active processes present significant geo-hazards to populations and offshore infrastructure that require monitoring and there could be commercial applications of technological developments needed for science. Some of the suggestions could involve studies in shallow coastal waters where ship costs are much reduced, addressing tighter funding constraints over the near term. The possibilities of measuring aspects of volcanic eruptions, flowing lava, turbidity currents and mass movements (landslides) are discussed. A further area of potential development is in greater collaboration between the ocean sciences. For example, it is well known in terrestrial geomorphology that biological agents are important in modulating erosion and the transport of sediments, ultimately affecting the shape of the Earth's surface in various ways. The analogous effect of biology on large-scale geomorphology in the oceans is also known but remains poorly quantified. Physical oceanographic models are becoming increasingly accurate and could be used to study further the patterns of erosion, particle transport and deposition in the oceans. Marine geological and geophysical data could in turn be useful for further verification of such models. Adapting them to conditions of past oceans could address the shorter-period movements, such as due to internal waves and tides, which have been barely addressed in palaeoceanography.

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Seismic velocity, anisotropy, and fluid pressure in the Barbados accretionary wedge from an offset vertical seismic profile with seabed sources

Cited by 16 publications

References 45 publications

Effective stress and pore pressure in the Nankai accretionary prism off the Muroto Peninsula, southwestern Japan

Effective stress and pore pressure in the Nankai accretionary prism off the Muroto Peninsula, southwestern Japan

The sub‐Himalayan fold‐thrust belt in the 1905 Kangra earthquake zone: A critical taper model perspective for seismic hazard analysis

Aspects of marine geoscience: a review and thoughts on potential for observing active processes and progress through collaboration between the ocean sciences

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