scholarly journals Predictive simulation of concurrent debris flows: How slope failure locations affect predicted damage

2021 ◽  
Author(s):  
Kazuki Yamanoi ◽  
Satoru Oishi ◽  
Kenji Kawaike ◽  
Hajime Nakagawa
Keyword(s):  
Debris Flows ◽  
Slope Failure ◽  
Predictive Simulation

Investigating the controls of submarine landslides and associated hazards in Pangnirtung Fiord, Eastern Baffin Island (Nunavut)

2021 ◽  
Author(s):  
Philip Sedore ◽  
Alexandre Normandeau ◽  
Vittorio Maselli
Keyword(s):  
High Latitude ◽  
Debris Flows ◽  
Slope Failure ◽  
Recurrence Time ◽  
High Recurrence Rate ◽  
Baffin Island ◽  
Submarine Landslides ◽  
Slope Failures ◽  
Near Surface ◽  
Submarine Slope

<p>High-latitude fiords are susceptible to hazardous subaerial and submarine slope failures. Recent investigations have shown that past slope failures in fiords of Greenland and Alaska have generated devastating landslide induced tsunamis. Since coastal communities inhabit these high-latitude fiords, it is critical to understand the slope failure recurrence time, their distribution, potential triggers, and ability to generate tsunamis. In this study, we identified > 50 near-surface submarine landslides in Pangnirtung Fiord, eastern Baffin Island, Nunavut, using multibeam bathymetric and sub-bottom profiler data, along with sediment gravity-cores collected in 2019. Morphometric and morphological analyses, along with sedimentological analyses, were carried out on submarine landslide deposits to quantify their spatial and temporal distribution throughout the fiord and to evaluate the factors that may have triggered the slope failures.</p><p>Combining bathymetric with topographic data from unmanned aerial vehicle imagery, we found that most of these landslide deposits are relatively small (~ 0.08 km<sup>2</sup>) and are associated with outwash fans and steep fiord sidewalls. However, since most slope failure head scarps lie between the intertidal zone and ~30 m water depth, they could not be mapped, which makes it challenging to determine the triggers of the submarine slope failures. Radiocarbon dating reveals that most of these surficial landslide deposits are younger than 500 years old and that they were most likely triggered at different times. This finding highlights a high recurrence rate of slope failures within the fiord, suggesting that localised triggers are responsible for slope failures within the fiord, as opposed to widespread, seismically induced triggers which do not occur as frequently in the study area. In addition, the elongated morphology of the landslide deposits and the varying degrees of landslide deposit surface roughness supports localised point-source triggers. Since most landslides are associated with subaerial outwash fans and deltas, we suggest that triggers of these relatively frequent submarine landslides within Pangnirtung Fiord include rapid floodwater input, subaerial debris flows, and sea-ice loading during low tide.</p><p>This research shows that slope failures in a high-latitude fiord are affected by the interaction of numerous subaerial and submarine processes, leading us to speculate that a potential increase in the frequency of subaerial debris flows and river floods due to climate change may increase the recurrence of submarine landslides.<strong> </strong></p>

Landsliding caused by Pleistocene glacial lake ponding–an example from central British Columbia

1987 ◽  
Vol 24 (4) ◽  
pp. 656-663 ◽  
Author(s):  
N. Eyles ◽  
John J. Clague
Keyword(s):  
British Columbia ◽  
Debris Flows ◽  
Large Scale ◽  
Slope Failure ◽  
Glacial Lake ◽  
Fraser River ◽  
Stability Of Slopes ◽  
History Of ◽  
The Stability ◽  
Glacier Advance

Sections cut through the Quaternary sediment fill of the Fraser River valley in central British Columbia provide evidence for large-scale landsliding during Pleistocene time. Especially notable are thick, laterally extensive diamict beds, consisting mainly of Tertiary rock debris, that occur near the base of glaciolacustrine sequences. These beds were deposited by subaqueous debris flows during one or more periods of lake ponding when advancing Pleistocene glaciers blocked the ancestral Fraser River. The association of diamict beds and glaciolacustrine sediments deposited during periods of glacier advance may indicate a genetic link between slope failure and lake filling. These observations (1) demonstrate the adverse effects of high pore pressures on the stability of slopes underlain by poorly indurated Tertiary rocks and (2) extend the known history of landslides involving these rocks back into the Pleistocene. Key words: landslides, debris flows, Pleistocene, glacial lake.

Predictive Simulation of Concurrent Debris Flow: How Slope Failure Locations Affect Predicted Damage

2020 ◽  
Author(s):  
Kazuki Yamanoi ◽  
Satoru Oishi ◽  
Kenji Kawaike ◽  
Hajime Nakagawa
Keyword(s):  
Standard Deviation ◽  
Debris Flow ◽  
Water Level ◽  
Slope Failure ◽  
Predictive Simulation ◽  
Relative Standard ◽  
Case Simulation ◽  
Failure Location ◽  
Downstream Area ◽  
Debris Flow Initiation

Predictive simulation of concurrent debris flow using only pre-disaster information has proven to be difficult as a result of problems in predicting the location of debris-flow initiation (i.e., slope failure). However, because catchment topography has concave characteristics, with all channels in a catchment joining each other as they flow downstream, it is possible to predict damage to downstream area using relatively inaccurate initiation points. Based on this, this paper presents methodologies employing debris-flow initiation points generated randomly using statistical slope failure prediction. A many-case simulation across numerous initiation points was performed to quantify the effect of slope-failure location in terms of deviations in the predicted water level and terrain deformation. It was found that the relative standard deviation diminished as the points approached the downstream area, indicating a location-based predictability effect.

scholarly journals Change Detection and Feature Extraction of Debris-Flow Initiation by Rock-Slope Failure Using Point Cloud Processing

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xiaoying He ◽  
Zeqing Yu ◽  
John M. Kemeny ◽  
Ann Youberg ◽  
Yunkun Wang
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Point Cloud ◽  
Slope Failure ◽  
Rock Slope ◽  
Point Cloud Data ◽  
Cloud Data ◽  
Cloud Processing ◽  
Point Cloud Processing ◽  
Debris Flow Initiation

Our understanding of debris-flow initiation by slope failure is restricted by the challenge of acquiring accurate geomorphic features of debris flows and the structural setting of the rock mass in the remote mountainous terrain. Point cloud data of debris flows in Sabino Canyon, Tucson, Arizona, July 2006, with initiation by joint-controlled rock slope were obtained using multitemporal LiDAR scanning. Topographic changes were detected by comparing historical LiDAR scanning data of this area since 2005 by adopting open-source CloudCompare software. The results showed persistent scour and erosion in the debris flows after 2006. Point cloud data of joint-controlled rock in the initiation zone were generated by the means of photogrammetry using Pix4D software. The joint planes, the dip direction and the dip value of the joint plane, the joint spacing, and the joint roughness were therefore acquired by point cloud processing. Our study contributes a foundation for analyzing the relationship between the rock features, the generation of slope failure, and the initiation of debris flows.

Landslides and surficial deposits in urban areas of British Columbia: A review

1982 ◽  
Vol 19 (3) ◽  
pp. 269-288 ◽  
Author(s):  
S. G. Evans
Keyword(s):  
British Columbia ◽  
Urban Areas ◽  
Debris Flows ◽  
Regional Variation ◽  
Slope Failure ◽  
Glacial Till ◽  
Geotechnical Characteristics ◽  
Surficial Deposits ◽  
Glaciomarine Sediments ◽  
Steep Slopes

Landslides in surficial deposits occur commonly in the urban environment of British Columbia. Three groups of surficial materials are especially prone to slope failure. These are glaciomarine sediments, glaciolacustrine deposits, and glacial till that mantles steep mountain slopes. The geological and geotechnical characteristics of these three materials are examined and discussed.The sensitivity, metastable fabric, and geological heterogeneity of glaciomarine sediments control their landslide behaviour. A regional variation in glaciolacustrine deposits is suggested. The Southern Interior and Columbia deposits are dominated by silt varves and those of the Northern Interior by clay varves. The silts are sensitive and collapsible under certain moisture and loading conditions. The effect of urbanisation on these silts in the semiarid Southern Interior is considerable. The retrogressive behaviour of slides in silts and clays in urban areas is also examined.Open-slope and channelled debris flows in till mantles are discussed. They occur mainly on steep slopes in the Coast Ranges as a response to heavy, relief-induced rainfall. The effect of urbanization on slope stability is also discussed.

Slope failures along the deformation front of the Cascadia margin: linking slide morphology to subduction zone parameters

2018 ◽  
Vol 477 (1) ◽  
pp. 47-67 ◽  
Author(s):  
Michael Riedel ◽  
Michelle M. Côté ◽  
Morelia Urlaub ◽  
Jacob Geersen ◽  
Nastasja A. Scholz ◽  
...  
Keyword(s):  
Debris Flows ◽  
Slope Failure ◽  
Accretionary Prism ◽  
Tsunami Generation ◽  
Slope Failures ◽  
Deformation Front ◽  
Acoustic Data ◽  
Submarine Slope ◽  
Cascadia Margin ◽  
Zone Parameters

AbstractMarine acoustic data are used to map and characterize submarine slope failure along the accretionary prism of Cascadia. Two main styles of slope failure are identified: (1) failures with curved head scarps, which are predominantly associated with incoherent debris-flow deposits; and (2) failures with rectangular head scarps, which are predominantly associated with intact sediment blocks. Rectangular head scarps mostly occur on thrust ridges with slope angles <16° and ridge heights <650 m, whereas curved head scarps occur predominantly on steeper and higher ridges. Off Vancouver Island, failure style and head-scarp geometry also change with ridge azimuth. We propose that the curved head scarps and debris flows may be a result of higher kinetic forcing of the downsliding sediments and a higher degree of mixing. At the more gently sloped, less elevated ridges, the kinetic forcing may be smaller, which leads to intact failure masses. Extensional faults at ridges with curved scarps may result from oversteepening and collapse of the sediments that cannot withstand their own weight due to limited internal shear strength. The slide geometries and potential controls on failure style may inform subsequent studies in assessing the risks for tsunami generation from submarine slope failures along the Cascadia margin.

Deepwater debrites and linked megaturbidites in confined basins: An example from the Onnuri Basin, East Sea of Korea

2021 ◽  
Vol 91 (1) ◽  
pp. 1-20
Author(s):  
Deniz Cukur ◽  
In-Kwon Um ◽  
Jong-Hwa Chun ◽  
Gwang-Soo Lee ◽  
Gee-Soo Kong ◽  
...  
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Slope Failure ◽  
Sedimentary Facies ◽  
High Amplitude ◽  
Seismic Facies ◽  
East Sea ◽  
Turbidity Currents ◽  
Radiocarbon Dates ◽  
Depositional Processes

ABSTRACT We analyzed data from seven piston cores, multi-channel seismic-reflection (MCS) and chirp profiles, and multibeam echosounder (MBES) data to study the distribution, emplacement time, sedimentary facies, and depositional processes of sediment-gravity-flow deposits in the Onnuri Basin, a confined basin in the East Sea. These data reveal that debris flows have traveled ca. 30 km downslope, forming a seismic facies consisting of stacked, wedge-shaped, transparent units separated by high-amplitude continuous reflectors. Analysis of piston cores shows three distinct sedimentary units, throughout the basin. The lowest unit, I, is a debrite containing numerous mud clasts of varying size and color distributed in a mud-rich matrix; it is absent over elevated basinal highs or ridges, such as the Onnuri Ridge, suggesting that local topography controls its distribution. The debrite forms a recognizable acoustically transparent layer on subbottom chirp profiles (av. 7 m thick), covers approximately 500 km2, and has an estimated volume of ∼ 3.5 km3. The overlying unit, II, contains normally graded beds composed of massive sand, laminated and cross-laminated sand and silt, and a thick cap of structureless mud. This unit is interpreted to be a megaturbidite deposited from turbidity currents that originated from the flow transformation of debris flows on the upper continental slope. The megaturbidite covers the entire basin (at least 650 km2), and has an average thickness of 2.8 m (maximum thickness of 4.35 m), and comprises a volume of 1.8 km3. Variations in grain size and sedimentary structures suggest that the megaturbidite was deposited by progressively waning flows that reflected off basin flanks and ridges. The thick (up to 3.65 m) structureless mud cap further indicates deposition in a confined basin. The sharp basal contact, together with the lack of hemipelagic sediments between debrite and overlying megaturbidite, suggest that both were deposited during the same flow event, likely to have originated from a single catastrophic slope failure. Collapsing slide material evolved into a debris flow, from which a turbidite formed by dilution of the debris flow. Radiocarbon dates suggest that the slope failure occurred about 13–11 ka, a time when sea level was ca. 50 m lower than at the present day. Hemipelagic sediments in the topmost unit, III-2, above the megaturbidite indicate that the basin has been stable since ca. 11 ka. We provide robust evidence that submarine slope failures evolve downslope into slides, debris flows, and finally, thick megaturbidites. This contribution highlights the importance of seafloor morphology on the distribution and stratigraphy of submarine flows in confined basins.

Fabrication of a Slope Failure Prediction Sensor using Miniaturized EC Sensor

2013 ◽  
Vol 133 (9) ◽  
pp. 278-283 ◽  
Author(s):  
Masato Futagawa ◽  
Mitsuru Komatsu ◽  
Hikofumi Suzuki ◽  
Yuji Takeshita ◽  
Yasushi Fuwa ◽  
...  
Keyword(s):  
Slope Failure ◽  
Failure Prediction
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