Application of MASW technology to identification of tidal flat stratigraphy and its geoenvironmental interpretation

Watabe, Yoichi; Sassa, Shinji

doi:10.1016/j.margeo.2008.03.007

Cited by 48 publications

(8 citation statements)

References 28 publications

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“…[12] The marked contrast in the bar-trough stratigraphy due to the suction-induced cyclic elastoplastic contraction has also been confirmed by the application of a high resolution surface-wave seismograph and by in situ sediment sampling and physical soil tests [Watabe and Sassa, 2008].…”

Section: Geophysical Evidencementioning

confidence: 90%

Persistent sand bars explained by geodynamic effects

Sassa¹,

Watabe²

2009

Geophysical Research Letters

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The persistent nature of intertidal sand bars has been the subject of much speculation concerning the hydrodynamic mechanisms involved, but its origin remains enigmatic. Here, we introduce salient geophysics in contrast to the physics of fluids above the sediments. The geophysical evidence combined with theoretical modeling and analysis demonstrates that the geodynamic processes ensuing during exposure periods have a profound impact, yielding the persistent nature of the intertidal bars under severe hydrodynamic forcing which would otherwise lead to unstable bar behavior. The feedback between the effects of the dynamics of suction, i.e. negative pore water pressure relative to atmospheric air pressure, and sediment transport and morphology is found to play a crucial role in the intertidal bar morphodynamics. Our finding may fundamentally alter the current perspective, leading to a new level of understanding, of sediment transport and bar behavior at waterfronts that are ubiquitous in rivers, estuaries, and coastal seas.

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Section: Geophysical Evidencementioning

confidence: 90%

Persistent sand bars explained by geodynamic effects

Sassa¹,

Watabe²

2009

Geophysical Research Letters

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“…The authors have been conducting multi-channel analysis of surface waves: MASW (Park et al 1999;Hayashi and Suzuki 2004) at intertidal flats with various characteristics (Watabe and Sassa 2008;. In this study, MASW survey was conducted along the arrays shown in Figure 1 at the artificial intertidal flat in Tokuyama-Kudamatsu Port, Yamaguchi, Japan.…”

Section: Multi-channel Analysis Of Surface Waves (Masw)mentioning

confidence: 99%

Safety assessment of an artificial intertidal flat using MASW technology

Watabe

Sassa

Kaneko

et al. 2015

JGS Special Publication

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Dredged soils from navigation channel or anchorage area have been used in reclamation of artificial intertidal flats in Japan. Immediately after the reclamation, because the dredged clay filled in the intertidal flat has not consolidated, a safety assessment system is strongly required to avoid depression of foot into an extremely soft soil at a place where sand capping is significantly thin. In addition, temporal variation of the dredged soils filled in the intertidal flats has not been clarified yet. In this study, a follow up research at an artificial intertidal flat in Tokuyama-Kudamatsu Port, Yamaguchi, Japan, was periodically conducted for several years since its completion of reclamation in 2008. Shear wave velocity obtained by MASW in the extremely soft sediments was only 25 m/s. Gradual increase with elapsed time in shear strength of dredged soil layer was mostly caused by chemical bonding (thixotropy effect) rather than densification (consolidation). Because MASW can describe both the thickness of sand capping and softness of the dredged soils, this technology is useful to assess the safety of artificial intertidal flats.

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“…Surface wave methods can be used to determine the textural properties of soils (Long and Donohue, 2007) and shallow subsurface stratigraphy (Watabe and Sassa, 2008). The method has also been employed for the study of karstic terrain and landforms (Thierry et al, 2004;Nasseri-Moghaddam et al, 2007).…”

Section: Seismicsmentioning

confidence: 99%