A hydrochemical study of urban landslides caused by heavy rain: Scarborough Bluffs, Ontario, Canada

1988 ◽  
Vol 25 (3) ◽  
pp. 455-466 ◽  
Author(s):  
N. Eyles ◽  
K. W. F. Howard
Keyword(s):  
Surface Runoff ◽  
Erosion Rate ◽  
Slope Failure ◽  
Heavy Rain ◽  
Slope Failures ◽  
Hydrochemical Study ◽  
Permeable Barriers ◽  
Glacial Clays ◽  
Lower Slope ◽  
Clayey Slope

Scarborough Bluffs is a 15 km long stretch of the Lake Ontario shoreline east of downtown Toronto. This heavily urbanized area currently represents Canada's most serious erosion problem. The worst affected zone is 1.5 km long and lies along South Marine Drive where 50 m high bluffs are failing by shallow retrogressive failures of jointed glacial clays over underlying deltaic sands and clays. The erosion rate is about four times that for the coastline as a whole.Heavy rains in the Toronto area in August and September 1986 produced a spate of slope failures and mud flows. Particularly heavy storms on September 10 and 29 triggered extensive retrogressive slope failures at South Marine Drive. Hydrochemical investigations of discharge waters suggest that slope failure was caused by surface runoff on the bluff top recharging lower slope areas by infiltration through joints in the upper clay capping. Discharge of water from the lower slope is impeded by less permeable barriers in the deltaic stratigraphy at the site and by a cover of clayey slope debris. Data suggest that provision for adequate drainage of the bluff top, by interceptor drains, is a prerequisite for controlling slope behaviour in the area. Key words: slopes, erosion, groundwater, hydrochemical, recharge, drainage.

Submarine canyons, slope failures and mass transport processes in southern Cascadia

2020 ◽  
Vol 500 (1) ◽  
pp. 453-475 ◽  
Author(s):  
Jenna C. Hill ◽  
Janet T. Watt ◽  
Daniel S. Brothers ◽  
Jared W. Kluesner
Keyword(s):  
Deep Water ◽  
Slope Failure ◽  
Water Channel ◽  
Transport Processes ◽  
Cascadia Subduction Zone ◽  
Submarine Landslides ◽  
Slope Failures ◽  
Submarine Canyons ◽  
Ground Shaking ◽  
Lower Slope

AbstractMarine turbidite records have been used to infer palaeoseismicity and estimate recurrence intervals for large (>Mw7) earthquakes along the Cascadia Subduction Zone. Conventional models propose that upper slope failures are funneled into submarine canyons and develop into turbidity flows that are routed down-canyon to deep-water channel and fan systems. However, the sources and pathways of these turbidity flows are poorly constrained, leading to uncertainties in the connections between ground shaking, slope failure and deep-water turbidites. We examine the spatial distribution of submarine landslides along the southern Cascadia margin to identify source regions for slope failures that may have developed into turbidity flows. Using multibeam bathymetry, sparker multichannel seismic and chirp sub-bottom data, we observe relatively few canyon head slope failures and limited evidence of large landslides on the upper and middle slope. Most of the submarine canyons are draped with sediment infill in the upper reaches and do not appear to be active sediment conduits during the recent sea-level highstand. In contrast, there is evidence of extensive mass wasting of the lower slope and non-channelized downslope flows. Contrary to previous studies, we propose that failures along the lower slope are the primary sources for deep-sea seismoturbidites in southern Cascadia.

scholarly journals The evolution of slope failures: mechanisms of rupture propagation

2004 ◽  
Vol 4 (1) ◽  
pp. 147-152 ◽  
Author(s):  
D. N. Petley
Keyword(s):  
Slope Failure ◽  
Complex Stress ◽  
Basal Region ◽  
Rupture Propagation ◽  
Slope Failures ◽  
Stress Regime ◽  
Detailed Surface ◽  
Landslide Mass ◽  
Region Data ◽  
Detailed Assessment

Abstract. Forecasting the occurrence of large, catastrophic slope failures remains very problematic. It is clear that in order advance this field a greater understanding is needed of the processes through which failure occurs. In particular, there is a need to comprehend the processes through which a rupture develops and propagates through the slope, and the nature of the inter-relationship between the stress and strain states of the landslide mass. To this end, a detailed analysis has been undertaken of the movement records for the Selborme Cutting slope failure, in which failure was deliberately triggered through pore pressure elevation. The data demonstrate that it is possible to determine the processes occurring in the basal region of the landslide, and thus controlling the movement of the mass, from the surface movement patterns. In particular, it is clear that the process of rupture development and propagation has a unique signature, allowing the development of the rupture to be traced from detailed surface monitoring. For landslides undergoing first time failure through rupture propagation, this allows the prediction of the time of failure as per the "Saito" approach. It is shown that for such predictions to be reliable, data from a number of points across the landslide mass are needed. Interestingly, due to the complex stress regime in that region, data from the crown may not be appropriate for failure prediction. Based upon these results, the application of new techniques for the detailed assessment of spatial patterns of the development of strain may potentially allow a new insight into the development of rupture surfaces and may ultimately permit forecasting of the temporal occurrence of failure.

Recurrent rock avalanches progressively dismantle mountain ridges in the Longmen Shan, China, most recently in the 2008 Wenchuan earthquake

2021 ◽  
Author(s):  
Janusz Wasowski ◽  
Maurice McSaveney ◽  
Luca Pisanu ◽  
Vincenzo Del Gaudio ◽  
Yan Li ◽  
...  
Keyword(s):  
Wenchuan Earthquake ◽  
Ambient Noise ◽  
Slope Failure ◽  
Mass Movement ◽  
Rock Avalanche ◽  
Ground Vibration ◽  
Source Area ◽  
Slope Failures ◽  
Rock Avalanches ◽  
Beichuan County

<p>Large earthquake-triggered landslides, in particular rock avalanches, can have catastrophic consequences. However, the recognition of slopes prone to such failures remains difficult, because slope-specific seismic response depends on many factors including local topography, landforms, structure and internal geology. We address these issues by exploring the case of a rock avalanche of >3 million m<sup>3</sup> triggered by the 2008 Mw7.9 Wenchuan earthquake in the Longmen Shan range, China. The failure, denominated Yangjia gully rock avalanche, occurred in Beichuan County (Sichuan Province), one of the areas that suffered the highest shaking intensity and death toll caused by co-seismic landsliding. Even though the Wenchuan earthquake produced tens of large (volume >1 million m<sup>3</sup>) rock avalanches, few studies so far have examined the pre-2008 history of the failed slope or reported on the stratigraphic record of mass-movement deposits exposed along local river courses. The presented case of the Yangjia gully rock avalanche shows the importance of such attempts as they provide information on the recurrence of large slope failures and their associated hazards. Our effort stems from recognition, on 2005 satellite imagery, of topography and morphology indicative of a large, apparently pre-historic slope failure and the associated breached landslide dam, both features closely resembling the forms generated in the catastrophic 2008 earthquake. The follow-up reconstruction recognizes an earlier landslide deposit exhumed from beneath the 2008 Yangjia gully rock avalanche by fluvial erosion since May 2008. We infer a seismic trigger also for the pre-2008 rock avalanche based on the following circumstantial evidence: i) the same source area (valley-facing, terminal portion of a flat-topped, elongated mountain ridge) located within one and a half kilometer of the seismically active Beichuan fault; ii) significant directional amplification of ground vibration, sub-parallel to the failed slope direction, detected via ambient noise measurements on the ridge adjacent to the source area of the 2008 rock avalanche and iii) common depositional and textural features of the two landslide deposits. Then, we show how, through consideration of the broader geomorphic and seismo-tectonic contexts, one can gain insight into the spatial and temporal recurrence of catastrophic slope failures  in Beichuan County and elsewhere in the Longmen Shan. This insight, combined with local-scale geologic and geomorphologic knowledge, may guide selection of suspect slopes for reconnaissance, wide-area ambient noise investigation aimed at discriminating their relative susceptibility to co-seismic catastrophic failures. We indicate the feasibility of such investigations through the example of this study, which uses 3-component velocimeters designed to register low amplitude ground vibration.</p>

scholarly journals A theoretical model for the initiation of debris flow in unconsolidated soil under hydrodynamic conditions

2014 ◽  
Vol 2 (6) ◽  
pp. 4487-4524 ◽  
Author(s):  
C.-X. Guo ◽  
J.-W. Zhou ◽  
P. Cui ◽  
M.-H. Hao ◽  
F.-G. Xu
Keyword(s):  
Theoretical Model ◽  
Debris Flow ◽  
Surface Runoff ◽  
Slope Failure ◽  
Fine Particles ◽  
Field Investigation ◽  
Hydrodynamic Theory ◽  
Mechanism Analysis ◽  
Flume Experiments ◽  
Initiation Mechanism

Abstract. Debris flow is one of the catastrophic disasters in an earthquake-stricken area, and remains to be studied in depth. It is imperative to obtain an initiation mechanism and model of the debris flow, especially from unconsolidated soil. With flume experiments and field investigation on the Wenjiagou Gully debris flow induced from unconsolidated soil, it can be found that surface runoff can support the shear force along the slope and lead to soil strength decreasing, with fine particles migrating and forming a local relatively impermeable face. The surface runoff effect is the primary factor for accelerating the unconsolidated slope failure and initiating debris flow. Thus, a new theoretical model for the initiation of debris flow in unconsolidated soil was established by incorporating hydrodynamic theory and soil mechanics. This model was validated by a laboratory test and proved to be better suited for unconsolidated soil failure analysis. In addition, the mechanism analysis and the established model can provide a new direction and deeper understanding of debris flow initiation with unconsolidated soil.

scholarly journals SLOPE FAILURE RISK ASSESSMENT MODELING USING TOPOGRAPHIC DATA AND NUMERICAL CALCULATION OF SOIL CONSERVATION BY TREE ROOT SYSTEMS

2019 ◽  
Vol IV-2/W5 ◽  
pp. 217-222
Author(s):  
T. Mori ◽  
T. Sugiyama ◽  
I. Hosooka ◽  
M. Nakata ◽  
K. Okano ◽  
...  
Keyword(s):  
Risk Assessment ◽  
At Risk ◽  
Slope Failure ◽  
Forest Type ◽  
Heavy Rain ◽  
Root Systems ◽  
Topographic Data ◽  
Relative Risk Assessment ◽  
External Forces ◽  
Heavy Rains

<p><strong>Abstract.</strong> In Japan, the frequency of sudden heavy rain events has recently increased, causing slope failures that in turn increase rates of damage to transit infrastructure such as railways and roads. To reduce this damage, there is a need to identify locations near railroad tracks that are at risk of slope failure. Thus, an assessment that predicts whether or not damage will occur due to external forces such as heavy rains is required, rather than a simple relative risk assessment based on identifying locations similar to those damaged in previous events. In this study, we developed a method for time series stability assessment of slopes during heavy rains using digital topographic data. This method uses topographic data to estimate topsoil thickness, which contributes to stability, and soil strength, which is affected by the root systems of vegetation on slopes. Using differences in these parameters between tree species and forest type, we were able to calculate slope stability and simulate slope failure during rainfall. The simulations allowed us to evaluate locations along routes where previous failures occurred, and to identify at-risk locations that have not yet experienced slope failure. This approach will improve forest management based on risk assessments for intensifying heavy rains.</p>

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

&lt;p&gt;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 &gt; 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.&lt;/p&gt;&lt;p&gt;Combining bathymetric with topographic data from unmanned aerial vehicle imagery, we found that most of these landslide deposits are relatively small (~ 0.08 km&lt;sup&gt;2&lt;/sup&gt;) 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.&lt;/p&gt;&lt;p&gt;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.&lt;strong&gt; &lt;/strong&gt;&lt;/p&gt;

scholarly journals Structure and dynamics of deep-seated slope failures in the Magura Flysch Nappe, outer Western Carpathians (Czech Republic)

2004 ◽  
Vol 4 (4) ◽  
pp. 549-562 ◽  
Author(s):  
I. Baron ◽  
V. Cilek ◽  
O. Krejci ◽  
R. Melichar ◽  
F. Hubatka
Keyword(s):  
Czech Republic ◽  
Slope Failure ◽  
Interdisciplinary Approach ◽  
Failure Surface ◽  
Late Glacial ◽  
Western Carpathians ◽  
Mass Movements ◽  
Slope Failures ◽  
Total Displacement ◽  
Outer Western Carpathians

Abstract. Deep-seated mass movements currently comprise one of the main morphogenetic processes in the Flysch Belt of the Western Carpathians of Central Europe. These mass movements result in a large spectrum of slope failures, depending on the type of movement and the nature of the bedrock. This paper presents the results of a detailed survey and reconstruction of three distinct deep-seated slope failures in the Raca Unit of the Magura Nappe, Flysch Belt of the Western Carpathians in the Czech Republic. An interdisciplinary approach has enabled a global view of the dynamics and development of these deep-seated slope failures. The three cases considered here have revealed a complex, poly-phase development of slope failure. They are deep-seated ones with depths to the failure surface ranging from 50 to 110m. They differ in mechanism of movement, failure structure, current activity, and total displacement. The main factors influencing their development have been flysch-bedrock structure, lithology, faulting by bedrock separation (which enabled further weakening through deep weathering), geomorphic setting, swelling of smectite-rich clays, and finally heavy rainfall. All of the slope failures considered here seem to have originated during humid phases of the Holocene or during the Late Glacial.

Assessment of Guar Gum Biopolymer Treatment toward Mitigation of Desiccation Cracking on Slopes Built with Expansive Soils

2017 ◽  
Vol 2657 (1) ◽  
pp. 78-88 ◽  
Author(s):  
Raju Acharya ◽  
Aravind Pedarla ◽  
Tejo V. Bheemasetti ◽  
Anand J. Puppala
Keyword(s):  
Factor Of Safety ◽  
Slope Failure ◽  
Soil Stabilization ◽  
Guar Gum ◽  
Expansive Soils ◽  
Environmental Benefits ◽  
Three Dimensions ◽  
Slope Failures ◽  
Lagrangian Analysis ◽  
Desiccation Cracking

Expansive soil embankments are prone to shallow slope failures caused by associated swell–shrink movements. Previous studies have confirmed that seasonal changes and corresponding volumetric changes are responsible for desiccation cracking, which is a major factor behind shallow slope failures of highway embankments. For the past few years, soil stabilization proved to be an effective way to mitigate the swell–shrink property of expansive clays. The current study addresses the feasibility of guar gum biopolymer in mitigating the swell–shrink behavior of clays and in turn making it possible to adopt them as stable geomaterials. The sustainable benefits of biopolymers far exceed the environmental benefits from conventional stabilizers that contractors typically use. This paper presents a comprehensive laboratory study, followed by finite difference modeling analysis, on biopolymeric guar gum–remediated expansive soils collected from shallow slope failure-prone areas. For this study, two dam locations, at Grapevine Lake and Joe Pool Lake, Texas, that were originally constructed with expansive soils, were considered. The engineering performance of biopolymer-treated soils was evaluated and an optimum dosage was recommended for mitigating desiccation cracking at the test sites. Slope stability analyses were conducted using Fast Lagrangian Analysis of Continua in Three Dimensions software by adopting laboratory-determined strength parameters to determine the range of the factor of safety for the slopes. The variation of the factor of safety computed with the inclusion of enhanced engineering parameters from guar gum treatments revealed the advantages of adopting this treatment.

scholarly journals Erosion Failure of a Soil Slope by Heavy Rain: Laboratory Investigation and Modified GA Model of Soil Slope Failure

2019 ◽  
Vol 16 (6) ◽  
pp. 1075 ◽  
Author(s):  
Xiaofei Jing ◽  
Yulong Chen ◽  
Changshu Pan ◽  
Tianwei Yin ◽  
Wensong Wang ◽  
...  
Keyword(s):  
Laboratory Investigation ◽  
Slope Failure ◽  
Slope Angle ◽  
Heavy Rain ◽  
Annual Rainfall ◽  
Soil Slope ◽  
Saturated Zone ◽  
Wetting Front ◽  
Rainfall Condition ◽  
The Impact

Rainfall has been identified as one of the main causes for slope failures in areas where high annual rainfall is experienced. The slope angle is important for its stability during rainfall. This paper aimed to determine the impact of the angle of soil slope on the migration of wetting front in rainfall. The results proved that under the same rainfall condition, more runoff was generated with the increase of slope angle, which resulted in more serious erosion of the soil and the ascent of wetting front. A modified Green-Ampt (GA) model of wetting front was also proposed considering the seepage in the saturated zone and the slope angle. These findings will provide insights into the rainfall-induced failure of soil slopes in terms of angle.

Fracturing within anticlines and its kinematic control on slope stability

2002 ◽  
Vol 8 (1) ◽  
pp. 19-33 ◽  
Author(s):  
Thomas C. Badger
Keyword(s):  
Slope Stability ◽  
Ground Water ◽  
Slope Failure ◽  
Mode I ◽  
Mode Ii ◽  
Shear Stresses ◽  
Fold Axis ◽  
Slope Failures ◽  
Kinematic Control ◽  
Discontinuity Sets

Abstract Anticlinal folding generates both bedding-parallel shear stresses and tensional stresses radial to the fold axis. These stresses typically produce two sets of discontinuities. Discontinuity set S 1 forms coincident with bedding (S 0 ) as a mode II fracture, and discontinuity set S 2 forms perpendicular to bedding and strikes parallel to the fold axis as a mode I fracture. For slopes that strike parallel to the fold axis, these two discontinuity sets may produce three structurally-controlled modes of slope failure. For slopes that are coincident with bedding, planar failures along S 0 /S 1 commonly occur and can be very large. Where bedding dips favorably into the slope, failures along joint set S 2 and across bedding can occur. Toppling failures are common to both of these slope configurations, along S 2 and S 0 /S 1 , respectively. Lastly, flat or shallow dipping S 0 /S 1 fractures, even those favorably oriented, and intersecting S 2 joints define blocks that can be mobilized by high ground-water pressures. An example is presented for each slope configuration to illustrate these kinematic controls on slope stability.

Sign in / Sign up

Export Citation Format

Share Document