SeaMARC II study of a giant submarine slump on the northern Chile continental slope

Li, Chang; Clark, Allen L.

doi:10.1080/10641199109379894

Cited by 10 publications

(6 citation statements)

References 8 publications

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“…They form beneath the seafloor under well-defined conditions of temperature and pressure, and they contain a huge amount of free-gas equivalent: 170 volumetric units of free methane at standard temperature and pressure in one volumetric unit of gas hydrate [Kvenvolden et al, 1984;Sloan, 1990]. As was demonstrated by Lee [1991, 1993] Another tectonic process, tectonic compression at subduction zones, was proposed by Li and Clark [1991] as one of several causes of slumping in lithified sediment on the landward wall of the Peru-Chile Trench. They presented a scenario for slope failure that is closely linked to subduction of the Nazca Plate beneath the noted that tall (>600 m) submarine slopes composed of carbonate sediment tend to be steeper than their siliclastic counterparts and approach a limiting angle of about 29 ø.…”

Section: Open Continental-margin Slopesmentioning

confidence: 94%

Submarine landslides

Hampton¹,

Lee²,

Locat³

1996

Reviews of Geophysics

916

643

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LONG-TERM GOALS My long term goals are to develop, test, and clearly present new quantitative methods for evaluating ' stresses in the earth's crust and to through new field observations and new mechanical analyses to contribute to a better understanding of geologic fracture phenomena, especially faulting, landsliding, joint formation, and dike intrusion. OBJECTIVES The main scientific objectives of this project are to identify and better understand the factors controlling where submarine landslide failure surfaces nucleate, how they propagate, how deformation accumulates in the incipient stages of landsliding, and to develop methods for analyzing these phenomena. A second objective is to reconcile predictions of fracture mechanics theory with observations of secondary fractures around faults. The landslide and faulting studies are linked because they both involve shear fracture, albeitunder different environmental conditions. The work also is undertaken with the objective of developing my graduate students as well-grounded research scientists. APPROACH This study is primarily theoretical and utilizes numerical stress analyses to understand sliding processes. Landslide failure surfaces and faults are modeled as fractures in elastic media using displacement discontinuity boundary element codes (e.g., Crouch and Starfield, 1983; Thomas, 1993). Fleming and Johnson (1989) proposed viewing landslide failure surfaces as fractures, and this concept is tested quantitatively here. The mechanical analyses for landslides have been conducted in both two-and three-dimensions and account for topography and stresses due to gravity. The stresses in a slope without a failure surface are examined to see where failure might nucleate. Stresses and displacements within a slope containing different failure surface geometries are then examined to understand how a failure surface might propagate and how the slope deforms in response. The model results are compared with observations made by other investigators to test the model predictions. For the faults, stress analyses have been conducted in three-dimensions to indicate the location, orientation, and size of secondary fractures. The mechanical analyses are then tested against my field observations of faults, collected as part of another project. Development of mechanical analysis methods is a major component of this research. IJTIG QUALITY JEZr%&Wm 4 20000627 025

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Section: Open Continental-margin Slopesmentioning

confidence: 94%

Submarine landslides

Hampton¹,

Lee²,

Locat³

1996

Reviews of Geophysics

916

643

View full text Add to dashboard Cite

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“…In carbonate platforms the oversteepening of slopes is attributed mainly to cementation and growth of reef communities (Schlager and Camber 1986). In addition to the factors mentioned above, faults have been suggested to control failures (Hampton et al 1978;Li and Clark 1991;Hine et al 1992). Faulting can directly oversteepen the slope and cause the slides to move by seismic shaking (active faulting) or just act as a predisposing factor by offering zones of weakness.…”

Section: Trigger Mechanismsmentioning

confidence: 98%

3-D Seismic Characterization of Submarine Landslides on a Miocene Carbonate Platform (Luconia Province, Malaysia)

Zampetti

Schlager

Konijnenburg

et al. 2004

Journal of Sedimentary Research

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3-D seismic reflection data and a variance cube are used to determine the architecture and investigate the triggering processes of submarine landslides affecting the flanks of a Miocene carbonate platform in the Luconia Province, Malaysia. The slide masses exhibit, in time-slice displays, chaotic, patchy seismic patterns, in otherwise smooth reflections. They lie basinward of the slide scar, tend to widen in the transport direction, and end in indistinct lobes. Slide scars appear as crescent-shaped embayments in otherwise straight or oval platform-edge contours. However, slide scars show planar morphology where they coincide with a fault zone. In vertical sections, the basal surfaces of the slides are steep concave slope segments (slide scar) that rapidly flatten where they dip under the slide masses. Slide masses appear as zones of discontinuous wavy reflections that wedge out in both upslope and downslope directions, extend for 1.5 km into the basin, and have a maximum thickness of 130 m. The slide deposit on the western flank is the result of at least two individual sliding events. Two seismically chaotic bodies are separated by a smooth reflection interpreted as an intercalation of hemipelagic mud between carbonaterich slide masses. Syndepositional faulting affects the geometry of the platform and the platform margins, particularly at the time of slope failure. We suggest that the slides were generated by the interplay of steep-slope progradation and faulting accompanied by seismic shocks.

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“…During sea level lowstands, dissociation of gas hydrates can trigger landslides [ Kayen and Lee , 1993], as can turbidity currents downcutting through steep‐walled canyons [ McAdoo et al , 2000]. Li and Clark [1991] propose that slope instability is enhanced along subduction boundaries where faulting and large magnitude earthquakes associated with plate subduction may promote slope failure. On margins with as much in common geologically and tectonically as Nankai and Cascadia, one would expect to see similar morphologies that reflect the dominant geomorphic process earthquakes.…”

Section: Introductionmentioning

confidence: 99%

Seafloor geomorphology of convergent margins: Implications for Cascadia seismic hazard

2004

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We compare the geomorphology of several convergent continental margins to constrain the seismic hazard of the Cascadia margin offshore Oregon, and present the possibility of a slow earthquake mechanism for a characteristic Cascadia event. The Cascadia seafloor has a very delicate bathymetry, with well‐preserved landslides and noneroded slopes approaching 20°, unusual for a margin that produces M∼9 earthquakes. Three‐dimensional seismic and multibeam bathymetry data from the Nankai Trough suggest ubiquitous erosion over the entire margin with a smooth lower slope, devoid of large landslides, as would be expected on an accretionary margin that produces M∼8.5 earthquakes. The accretionary Makran (Pakistan) and Kodiak (Alaska) margins have evidence of mass wasting and smooth lower slopes that lack large landslides. The nonaccreting Nicaraguan, Sanriku, and Aleutian margins have large, well‐preserved landslides that add roughness elements to the slope, and have produced anomalously large tsunami, suggesting a slow source mechanism. Quantitative analysis of the lower slope roughness suggests the Cascadia has a characteristic geomorphology substantially different than the other sedimented convergent margins. The geomorphology, heat flow, pore pressure regime, and accounts of the 1700 “megathrust” event suggest a possible characteristic earthquake with a slow source mechanism. Rupture velocity would be high enough to be tsunamigenic, but accelerations would be low such that downslope erosion is minimal. To make the distinction between a slow and rapid source mechanism is critical in planning for seismic hazard in the Pacific Northwest.

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SeaMARC II study of a giant submarine slump on the northern Chile continental slope

Cited by 10 publications

References 8 publications

Submarine landslides

Submarine landslides

3-D Seismic Characterization of Submarine Landslides on a Miocene Carbonate Platform (Luconia Province, Malaysia)

Seafloor geomorphology of convergent margins: Implications for Cascadia seismic hazard

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