scholarly journals Evidence for surface sediment remobilization by earthquakes in the Nankai forearc region from sedimentary records

2018 ◽  
Vol 477 (1) ◽  
pp. 37-45 ◽  
Author(s):  
Natsumi Okutsu ◽  
Juichiro Ashi ◽  
Asuka Yamaguchi ◽  
Tomohisa Irino ◽  
Ken Ikehara ◽  
...  
Keyword(s):  
Surface Sediment ◽  
Fine Sand ◽  
Turbidity Currents ◽  
Silty Clay ◽  
Submarine Landslides ◽  
Sedimentary Processes ◽  
Piston Core ◽  
Radiocarbon Age ◽  
Sedimentary Records ◽  
Forearc Region

AbstractSubmarine landslides triggered by earthquakes can generate turbidity currents. Recently, several studies have reported that the remobilization of surface sediment triggered by earthquakes can also generate turbidity currents. Such sedimentary processes may be influenced by sediment characteristics, seafloor morphology and seismic motions. Here, we verify surface sediment remobilization using sedimentary records from the Nankai forearc region, SW Japan. We collected multi-core and piston core samples from a small confined basin, mainly composed of silty clay or very fine sand. Radiocaesium measurements of the multi-core show consistently high values in the upper 17 cm and low values below this depth. Rapid sediment deposition after 1950 is assumed, and the most likely cause is the 2004 off the Kii Peninsula earthquake. Based on calculations using bathymetric maps and palaeocurrent data, settlement of the upper 17 cm can be explained by redeposition of the surface (c. 1 cm) slope sediment around the basin. Muddy turbidites are also identified in the piston core. The gap in radiocarbon age observed around 2.0 m bsf (metres below seafloor) implies similar sedimentary processes. Our study represents the first examination of surficial remobilization from sedimentary cores in the Nankai forearc region.

scholarly journals Design and Application of an In Situ Test Device for Rheological Characteristic Measurements of Liquefied Submarine Sediments

2021 ◽  
Vol 9 (6) ◽  
pp. 639
Author(s):  
Hong Zhang ◽  
Xiaolei Liu ◽  
Anduo Chen ◽  
Weijia Li ◽  
Yang Lu ◽  
...  
Keyword(s):  
Yellow River ◽  
Rheological Characteristic ◽  
Yellow River Delta ◽  
Turbidity Currents ◽  
Rheological Characteristics ◽  
Submarine Landslides ◽  
Test Device ◽  
Offshore Area ◽  
In Situ Test

Liquefied submarine sediments can easily lead to submarine landslides and turbidity currents, and cause serious damage to offshore engineering facilities. Understanding the rheological characteristics of liquefied sediments is critical for improving our knowledge of the prevention of submarine geo-hazards and the evolution of submarine topography. In this study, an in situ test device was developed to measure the rheological properties of liquefied sediments. The test principle is the shear column theory. The device was tested in the subaqueous Yellow River delta, and the test results indicated that liquefied sediments can be regarded as “non-Newtonian fluids with shear thinning characteristics”. Furthermore, a laboratory rheological test was conducted as a contrast experiment to qualitatively verify the accuracy of the in situ test data. Through the comparison of experiments, it was proved that the use of the in situ device in this paper is suitable and reliable for the measurement of the rheological characteristics of liquefied submarine sediments. Considering the fact that liquefaction may occur in deeper water (>5 m), a work pattern for the device in the offshore area is given. This novel device provides a new way to test the undrained shear strength of liquefied sediments in submarine engineering.

Sedimentary processes in the Selvage sediment-wave field, NE Atlantic: new insights into the formation of sediment waves by turbidity currents

Sedimentology ◽  
2000 ◽  
Vol 47 (6) ◽  
pp. 1181-1197 ◽  
Author(s):  
Russell B. Wynn ◽  
Philip P. E. Weaver ◽  
Gemma Ercilla ◽  
Dorrik A. V. Stow ◽  
Douglas G. Masson
Keyword(s):  
Wave Field ◽  
Turbidity Currents ◽  
Ne Atlantic ◽  
Sedimentary Processes ◽  
Sediment Wave ◽  
Sediment Waves

Essai d'interpretation du mecanisme des courants de turbidite

1962 ◽  
Vol S7-IV (6) ◽  
pp. 849-856
Author(s):  
Wladimir D. Nesteroff
Keyword(s):  
Fine Sand ◽  
Turbidity Current ◽  
Abyssal Plain ◽  
Upper Ocean ◽  
Turbidity Currents ◽  
Current Pulses ◽  
Coarse To Fine

Abstract When the mechanism of turbidity currents was first proposed, it was thought that ooze deposits, which alternated with coarse to fine sand, were deposited on abyssal plains by pelagic sedimentation between turbidity current pulses. Later it was thought that concentrations of calcareous bioclastic material in the upper part of the ooze pointed to turbidity current deposition of the sand and lower part of the ooze, with only the upper ooze a result of pelagic sedimentation. Because CaCO <sub>3</sub> tests dissolve in sinking, no calcareous tests of upper ocean origin are found below 5500 to 5600 m. However, a study of terrigenous turbidites from abyssal plain samples taken at depths exceeding 5900 m which follow the sand to ooze sequence with foraminiferal concentrations in the upper ooze demonstrate that the beds are turbidite alone. It is hypothesized that any pelagic deposits forming between turbidity currents would be eroded away at the beginning of each pulse and that the fossil concentrations in the upper ooze result from delayed settling of the gas or protoplasm filled tests.

The Sedimentary Structures and Depositional Mechanics of Certain Ordovician Turbidites, Cloridorme Formation, Gaspé Peninsula, Quebec

1975 ◽  
Vol 12 (11) ◽  
pp. 1934-1952 ◽  
Author(s):  
Keith Skipper ◽  
Gerard V. Middleton
Keyword(s):  
Large Scale ◽  
Fine Sand ◽  
Coarse Sand ◽  
Turbidity Currents ◽  
Upstream Migration ◽  
High Concentration ◽  
Sedimentary Structures ◽  
The North ◽  
Gaspe Peninsula ◽  
Gaspé Peninsula

Turbidites, belonging to the β1, member, Cloridorme Formation, are exposed on the north shore of the Gaspé Peninsula, Quebec. Their structural attitude is such that vertical sections through turbidite beds are exposed on the wave-cut platform and their strike is approximately parallel to the paleocurrent direction, as shown by sole marks on the bases of beds.Certain thick turbidite beds, in a distal position, display a sequence of sedimentary structures which differs from the sequence defined by Bouma. Three broad divisions are recognized: a basal division consists of either limestone or quartz granule to pebble conglomerate (0–4 cm thick) or coarse sand graywacke or calcareous wacke (0–15 cm thick). Basal divisions of calcareous wacke frequently display ripple-lamination, parallel lamination, or upstream-inclined laminae. Where the upstream inclined laminae form a single set, they occur below a sinuous profile (wavelength 40–80 cm, and amplitude 2–5 cm).A second division (0–330 cm thick) consists in most places of spindle- or globular-shaped calcareous nodules scattered in an argillaceous host. In some beds, streaking and lobing of light colored, carbonate bearing material is associated with these nodules. Internal hemi-ellipsoid structures, arranged en echelon and convex towards the base of the bed, are displayed from the second division. The upper division consists of fine grained siltstone and shale.The upstream-inclined laminae in the basal division of calcareous wacke beds are interpreted as being the result of the upstream migration of antidunes. The nodules within the second division developed as 'pseudo-nodules'. The hemi-ellipsoid structures resemble damped, large scale (macroturbulent) eddies associated with the flow of dense grain dispersions.Correlation of these beds has been achieved over a distance of 12 km. Basal divisions of granule and pebble conglomerate persist over this distance and show that coarse particles may be transported by turbidity currents over long distances. The sedimentary structures of the basal divisions of several calcareous wacke beds might be interpreted as the result of either an increase in flow regime downcurrent, or of nonpreservation of structures at up-current localities.The beds were probably deposited from turbidity currents composed largely of mud and fine sand, but containing a zone of coarse grains concentrated near the bed. The basal division was deposited from this lower zone and a period of traction formed rippled, flat, or antidune bed forms. Stratification in the basal division was preserved by the rapid deposition on top of sediment that settled en masse from the subsequent high concentration body of the current. The formation of a succession of 'quick' beds led to the sedimentation of the second division. The flows responsible for the sequence of structures observed and the downcurrent persistence of the beds probably approached closely a state of 'autosuspension'.

Locomotion and feeding traces in Champlain Sea subaqueous outwash deposits near Ottawa, Canada

1990 ◽  
Vol 27 (11) ◽  
pp. 1495-1503 ◽  
Author(s):  
Dana L. Naldrett
Keyword(s):  
Depositional Environment ◽  
Close Association ◽  
Circular Cross Section ◽  
Fine Sand ◽  
Bedding Plane ◽  
Life Forms ◽  
Silty Clay ◽  
Bedding Planes ◽  
Algae And Bacteria ◽  
Medium Silt

Locomotion and feeding traces (repichnia and fodichnia) observed on bedding planes of rhythmically bedded subaqueous outwash deposits in the Brazeau sand pit, Nepean, Ontario, Canada, are the first bedding-plane traces described in detail from the western Champlain Sea. The Planolites–Palaeophycus-like and Taenidium-like traces are cylindrical with circular cross section, smooth sided, unlined, sinuous, sometimes branching, and sometimes meniscate. Organisms producing the traces are tentatively identified as errant polychaetes or nemerteans. The enclosing sediments are rhythmic couplets of alternating fine sand and silt layers overlain by silty clay and fine–medium silt layers. The occurrence of traces within the uppermost portion of the coarse unit, and within the coarser, upper portion of the overlying fine unit, and the rhythmic alternation of coarse and fine layers suggest these deposits may be varves. The traces formed during the more biologically suitable summer months but were preserved only during the latter portion of the summer. Traces are distributed on bedding planes in close association with bedforms and show a high correlation with the substrate and possibly the hydrodynamic regime. This is interpreted as indicating a strong preference in feeding behaviour. The presence of traces in the subaqueous outwash environment necessitates rethinking of the depositional environment to include the presence of errant polychaetes, nemerteans or similar organisms, and the lower life-forms such as epontic algae and bacteria on which they live.

scholarly journals Slow build-up of turbidity currents triggered by a moderate earthquake in the Sea of Marmara

2021 ◽  
Author(s):  
Pierre Henry ◽  
Sinan Özeren ◽  
Nurettin Yakupoğlu ◽  
Ziyadin Çakir ◽  
Emmanuel de Saint-Léger ◽  
...  
Keyword(s):  
Sediment Resuspension ◽  
Turbidity Current ◽  
Turbidity Currents ◽  
Central Basin ◽  
Sea Of Marmara ◽  
Sedimentary Records ◽  
Strong Current ◽  
Moderate Earthquake ◽  
Basin Floor ◽  
Hydrodynamic Processes

Abstract. Earthquake-induced submarine slope destabilization is known to cause debris flows and turbidity currents, but the hydrodynamic processes associated with these events remain poorly understood. Records are scarce and this notably limits our ability to interpret marine paleoseismological sedimentary records. An instrumented frame comprising a pressure recorder and a Doppler recording current meter deployed at the seafloor in the Sea of Marmara Central Basin recorded consequences of a MW = 5.8 earthquake occurring Sept 26, 2019 and of a Mw = 4.7 foreshock two days before. The smaller event caused sediment resuspension but no strong current. The larger event triggered a complex response involving a mud flow and turbidity currents with variable velocities and orientations, which may result from multiple slope failures. A long delay of 10 hours is observed between the earthquake and the passing of the strongest turbidity current. The distance travelled by the sediment particles during the event is estimated to several kilometres, which could account for a local deposit on a sediment fan at the outlet of a canyon, but not for the covering of the whole basin floor. We show that after a moderate earthquake, delayed turbidity current initiation may occur, possibly by ignition of a cloud of resuspended sediment. Some caution is thus required when tying seismoturbidites with earthquakes of historical importance. However, the horizontal extent of the deposits should remain indicative of the size of the earthquake.

Manuring of potatoes on fen silt soils in Holland, Lincolnshire

1973 ◽  
Vol 80 (2) ◽  
pp. 269-281 ◽  
Author(s):  
C. Berryman ◽  
T. Batey ◽  
T. H. Caldwell ◽  
D. A. Boyd
Keyword(s):  
Crop Production ◽  
Soil Analysis ◽  
Organic Matter Content ◽  
Fine Sand ◽  
Coarse Sand ◽  
Matter Content ◽  
Silty Clay ◽  
Alluvial Deposits ◽  
K Fertilizer ◽  
P Fertilizer

SummaryThe fen silts bordering the Wash are among the most important soils for crop production in eastern England. Derived from marine alluvial deposits occurring naturally or as a result of reclamation, they form deep almost stoneless soils containing little coarse sand but much fine sand and silt.Seven textural classes, ranging from loamy fine sand to silty clay, can be distinguished, but these can be grouped into (1) light silts, typically deep very fine sandy loams with a large available water-holding capacity but weakly developed structure; (2) medium silts, silty loams; and (3) heavy silts, silt loams or silty clay loams, less porous and more retentive of moisture than the light silts.Formerly under grass, the silts were at first capable of growing good crops of potatoes with P fertilizer alone, but as their organic-matter content decreased, potatoes became increasingly responsive to N.In 18 potato manurial experiments on silt soils in Holland, Lincolnshire, done between 1953 and 1963, the mean response to N was much larger than on most English soils, but response differed greatly from site to site and year to year; in most trials N was particularly effective in increasing tuber size and yield of ware. With long-continued use of P fertilizer, residues have accumulated and, particularly on light and medium silts, responses were quite small and differed little between sites; P tended to increase tuber numbers, and so to decrease ware percentage. Most silt soils are rich in K, and only small responses to K fertilizer can be expected, but on a few sites on the light silts, identified by soil analysis as being comparatively poor in K, potatoes responded well. Using these experimental results, recommendations are given for the manuring of potatoes on silt soils.Cooking tests showed little consistent effect of manurial treatment on the amount or degree of tuber blackening.

scholarly journals Turbidity Currents, Submarine Landslides and the 2006 Pingtung Earthquake off SW Taiwan

2008 ◽  
Vol 19 (6) ◽  
pp. 767 ◽  
Author(s):  
Shu-Kun Hsu ◽  
Jackie Kuo ◽  
Chung-Liang Lo ◽  
Ching-Hui Tsai ◽  
Wen-Bin Doo ◽  
...  
Keyword(s):  
Turbidity Currents ◽  
Submarine Landslides
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