scholarly journals Enhanced landslide mobility by basal liquefaction: The 2014 State Route 530 (Oso), Washington, landslide

2019 ◽  
Vol 132 (3-4) ◽  
pp. 451-476 ◽  
Author(s):  
Brian D. Collins ◽  
Mark E. Reid
Keyword(s):  
Slope Failure ◽  
High Mobility ◽  
Structure Mapping ◽  
Ground Shaking ◽  
Sequence Of Events ◽  
Landslide Mobility ◽  
Sand Boils ◽  
Slide Material ◽  
Geotechnical Testing ◽  
Undrained Loading

AbstractLandslide mobility can vastly amplify the consequences of slope failure. As a compelling example, the 22 March 2014 landslide near Oso, Washington (USA), was particularly devastating, traveling across a 1-km+-wide river valley, killing 43 people, destroying dozens of homes, and temporarily closing a well-traveled highway. To resolve causes for the landslide’s behavior and mobility, we conducted detailed postevent field investigations and material testing. Geologic and structure mapping revealed a progression of geomorphological structures ranging from debris-flow lobes at the distal end through hummock fields, laterally continuous landslide blocks, back-rotated blocks, and finally colluvial slides and falls at the landslide headscarp. Primary structures, as well as stratigraphic and vegetation patterns, in the landslide deposit indicated rapid extensional motion of the approximately 9 × 106 m3 source volume in a closely timed sequence of events. We identified hundreds of transient sand boils in the landslide runout zone, representing evidence of widespread elevated pore-water pressures with consequent shear-strength reduction at the base of the slide. During the event, underlying wet alluvium liquefied and allowed quasi-intact slide hummocks to extend and translate long distances across the flat valley. Most of the slide material itself did not liquefy. Using geotechnical testing and numerical modeling, we examined rapid undrained loading, shear and collapse of loose saturated alluvium, and strong ground shaking as potential liquefaction mechanisms. Our analyses show that some layers in the alluvium can liquefy when sheared, as could occur with rapid undrained loading. Simultaneous ground shaking could have contributed to pore-pressure generation as well. Two key elements, a large and rapid failure overriding wet liquefiable sediments, enabled the landslide’s high mobility. Basal liquefaction may enhance mobility of other landslides in similar settings.

Enhanced landslide mobility promoted by liquefaction of underlying sediments: Evidence from detailed field, lab, and modelling investigations of the deadly Oso, USA landslide

2020 ◽  
Author(s):  
Mark Reid ◽  
Brian Collins
Keyword(s):  
Debris Avalanche ◽  
Potential Effect ◽  
River Valley ◽  
Deformation Analysis ◽  
Ground Shaking ◽  
Glacial Sediments ◽  
Landslide Mass ◽  
Landslide Mobility ◽  
Enhanced Mobility ◽  
Sand Boils

<p>Enhanced landslide mobility can project devastation across extensive areas, greatly affecting hazard and risk. Despite this importance, assessing potential mobility can be challenging as underlying causes of enhanced mobility vary. Liquefaction can dramatically decrease shear resistance and promote mobility, and pervasive liquefaction is well known to boost the mobility of debris flows and other flow slides. However, liquefaction’s potential effect on more coherent slide masses can be difficult to identify in the field. The 2014 Oso, Washington (USA) debris avalanche provides an exceptional opportunity to understand specific causes of liquefaction and enhanced mobility. The slide was more mobile than typical debris avalanches, sweeping over 1 km across a flat alluvial plain to the opposite side of the river valley and killing 43 people as it travelled. Following the 2014 event, we performed detailed investigations aimed at illuminating the event sequence and the mechanisms promoting mobility, with a strong focus on the role of liquefaction.</p><p>The landslide initiated in stratified glacial materials and created a variety of landslide deposit types, including a widespread debris-avalanche hummock field covering much of the formerly flat river valley. Our field investigations revealed clear and widespread evidence for sub-bottom (basal) liquefaction as the cause for the slide’s long reach. Soon after the slide event, we mapped more than 350 sand boils – classic indicators of liquefaction – as both isolated vents and groups of multiple vents within the hummock field. We found sand boils in the depressions between hummocks; the hummocks themselves were not liquefied and commonly contained rafted materials such as intact pieces of glacial stratigraphy and forest floor on their surfaces. The sand boils erupted through a variety of glacial sediments, including lacustrine clays. Sand boil grain-size characteristics most closely matched the underlying alluvial sands, rather than the overriding glacial sediments. Evidence of sand boils was transient; most features were eroded from the landscape within a year.</p><p>Liquefaction can be induced by several mechanisms, including rapid loading, shearing of loose contractive sediment, and cyclical loading during ground shaking. Given these plausible mechanisms, we used a fully coupled fluid-sediment elastic deformation analysis, as well as triaxial geotechnical testing of the alluvium, to assess potential liquefaction of the materials overrun by the Oso slide. Our results demonstrate that the large failure rapidly loading loose, already wet alluvial sediments likely resulted in their liquefaction. The greatly reduced shear strength of the liquefied alluvium enabled enhanced mobility of the overriding landslide mass on a liquefied base. This process differs from liquefaction of the slide material itself and is therefore not directly dependent on slide-mass properties. Liquefaction of underlying sediments, similar to that observed at Oso, may have enhanced the mobility of other large, coherent landslides in Europe and Asia.</p>

scholarly journals Geological and Structural Control on Localized Ground Effects within the Heunghae Basin during the Pohang Earthquake (MW 5.4, 15th November 2017), South Korea

Geosciences ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 173 ◽  
Author(s):  
Sambit Naik ◽  
Young-Seog Kim ◽  
Taehyung Kim ◽  
Jeong Su-Ho
Keyword(s):  
South Korea ◽  
Structural Control ◽  
Seismic Waves ◽  
Tectonic Setting ◽  
Lateral Spreading ◽  
Soil Liquefaction ◽  
Ground Shaking ◽  
Potential Mapping ◽  
Sand Boils ◽  
Ground Effects

On 15th November 2017, the Pohang earthquake (Mw 5.4) had strong ground shaking that caused severe liquefaction and lateral spreading across the Heunghae Basin, around Pohang city, South Korea. Such liquefaction is a rare phenomenon during small or moderate earthquakes (MW < 5.5). There are only a few examples around the globe, but more so in the Korean Peninsula. In this paper, we present the results of a systematic survey of the secondary ground effects—i.e., soil liquefaction and ground cracks—developed during the earthquake. Most of the liquefaction sites are clustered near the epicenter and close to the Heunghae fault. Based on the geology, tectonic setting, distribution, and clustering of the sand boils along the southern part of the Heunghae Basin, we propose a geological model, suggesting that the Heunghae fault may have acted as a barrier to the propagation of seismic waves. Other factors like the mountain basin effect and/or amplification of seismic waves by a blind thrust fault could play an important role. Liquefaction phenomenon associated with the 2017 Pohang earthquake emphasizes that there is an urgent need of liquefaction potential mapping for the Pohang city and other areas with a similar geological setting. In areas underlain by extensive unconsolidated basin fill sediments—where the records of past earthquakes are exiguous or indistinct and there is poor implementation of building codes—future earthquakes of similar or larger magnitude as the Pohang earthquake are likely to occur again. Therefore, this represents a hazard that may cause significant societal and economic threats in the future.

scholarly journals Mineralogical and Physico-chemical Properties of Halloysite-bearing Slip Surface Material From a Landslide During the 2018 Eastern Iburi Earthquake, Hokkaido

2020 ◽  
Author(s):  
Jun Kameda
Keyword(s):  
Colloidal Stability ◽  
Slip Surface ◽  
Flow Behavior ◽  
High Capacity ◽  
Chemical Properties ◽  
High Mobility ◽  
Electrophoretic Analysis ◽  
Surface Material ◽  
Solution Ph ◽  
Ground Shaking

Abstract Destructive landslides were triggered by the 6.7 Mw Eastern Iburi earthquake that struck southern Hokkaido, Japan on 6 September 2018. Heavy rainfall on 4 September in addition to intermittent rainfall around the Iburi Tobu area saturated and weakened altered volcanoclastic soils containing halloysite minerals, making them susceptible to failure because of the earthquake’s strong ground motion. The landslides exhibited laminar flow behavior, with long runouts along gentle hill slopes. This study investigated the mineralogical and physicochemical properties of the halloysite-bearing slip surface material with the aim of understanding weakening and post-failure behaviors during the landslides. Halloysite in the slip surface had irregular-to-hollow-spherical morphology with higher mesopore volumes than tubular halloysite, which is related to a high capacity for water retention after rainfall. To reproduce possible chemical changes in the slip surface during rainfall, the sample was immersed in varying amounts of rainwater; solution pH increased and ionic strength decreased with increasing water content. These findings, alongside electrophoretic analysis, suggest that rainwater infiltration could have increased the absolute zeta potential value of the slip surface material. It is suggested that rainfall before the earthquake enhanced the colloidal stability of halloysite particles within the slip surface, owing to an increase in electrostatic repulsion. This decreased the material’s cohesive strength, which might have led to destabilization of the slope during ground shaking generated by the earthquake, and subsequent high-mobility flow after failure.

scholarly journals Hazard-Consistent Earthquake Scenario Selection for Seismic Slope Stability Assessment

2020 ◽  
Vol 12 (12) ◽  
pp. 4977
Author(s):  
Alexey Konovalov ◽  
Yuriy Gensiorovskiy ◽  
Andrey Stepnov
Keyword(s):  
Slope Stability ◽  
Seismic Hazard ◽  
Ground Motion ◽  
Slope Failure ◽  
Probabilistic Approach ◽  
Seismic Loading ◽  
Time Interval ◽  
Total Probability ◽  
Ground Shaking ◽  
Earthquake Scenario

Design ground shaking intensity, based on probabilistic seismic hazard analysis (PSHA) maps, is most commonly used as a triggering condition to analyze slope stability under seismic loading. Uncertainties that are associated with expected ground motion levels are often ignored. This study considers an improved, fully probabilistic approach for earthquake scenario selection. The given method suggests the determination of the occurrence probability of various ground motion levels and the probability of landsliding for these ground motion parameters, giving the total probability of slope failure under seismic loading in a certain time interval. The occurrence hazard deaggregation technique is proposed for the selection of the ground shaking level, as well as the magnitude and source-to-site distance of a design earthquake, as these factors most probably trigger slope failure within the time interval of interest. An example application of the approach is provided for a slope near the highway in the south of Sakhalin Island (Russia). The total probability of earthquake-induced slope failure in the next 50 years was computed to be in the order of 16%. The scenario peak ground acceleration value estimated from the disaggregated earthquake-induced landslide hazard is 0.15g, while the 475-year seismic hazard curve predicts 0.3g. The case study highlights the significant difference between ground shaking scenario levels in terms of the 475-year seismic hazard map and the considered fully probabilistic approach.

Slope failures associated with the 1988 Saguenay earthquake, Quebec, Canada

1992 ◽  
Vol 29 (1) ◽  
pp. 117-130 ◽  
Author(s):  
Guy Lefebvre ◽  
Denis Leboeuf ◽  
Pierre Hornych ◽  
Luc Tanguay
Keyword(s):  
Granular Material ◽  
Key Words ◽  
Slope Failure ◽  
Failure Surface ◽  
Slope Failures ◽  
Clay Deposits ◽  
Sensitive Clay ◽  
Static Conditions ◽  
Undrained Loading ◽  
Natural Slopes

Nine case records of slope failure during the Saguenay earthquake are documented, including five in granular embankments, two in natural slopes in granular material with small embankments at the top, and two in sensitive clay. The bedrock motion during the earthquake is well documented; each failure is related to the most probable bedrock motion at the site (0.05 to 0.15 g). For the seven cases of failure in granular slopes, the reserve of stability under static conditions was relatively low before the earthquake, and only a small additional undrained loading was necessary to develop failure. Two slope failures occurred in extrasensitive clay deposits containing no visible lens or layer of silt or sand. Silty or sandy materials have been identified only at the clay–till contact. It is believed that in at least one of the sites a portion of the failure surface developed at the inclined clay–till contact. Key words : slope failure, earthquake, sensitive clays, embankment fill, stability, granular material.

scholarly journals 1-D inversion analysis of a shallow landslide triggered by the 2018 Eastern Iburi earthquake in Hokkaido, Japan

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Jun Kameda ◽  
Atsushi Okamoto
Keyword(s):  
Slope Failure ◽  
Flow Model ◽  
High Mobility ◽  
Shallow Landslide ◽  
Shallow Landslides ◽  
Viscoplastic Fluid ◽  
Rheological Parameters ◽  
Slope Length ◽  
Flow Duration ◽  
Inversion Analysis

AbstractDestructive landslides were triggered by the 6.7 Mw Eastern Iburi earthquake that struck southern Hokkaido, Japan, on 6 September 2018. In this study, we carried out 1-D inversion analysis of one of the shallow landslides near the epicenter using a Bing debris-flow model. At this site, the slope failure comprised cover soil with an initial down-slope length of ~ 80 m and a thickness of ~ 7 m on a slope with < 20° dip. The landslide moved southeastward with a run-out distance of ~ 100 m. Inversion analysis of the post-failure deposit geometry was conducted with the Markov Chain Monte Carlo method (MCMC) to optimize the Bingham rheological parameters of the debris. The analysis reproduced several features of the deposit geometry with a yield stress of ~ 1500 Pa and dynamic viscosity of 800–3000 Pa s. The results suggest that the shallow landslide can be approximated by the flow of a viscoplastic fluid with high-mobility debris and a maximum frontal velocity of 6–9 m/s, with a flow duration of 2–4 min.

scholarly journals Impacts of surface fault rupture on residential structures during the 2016 Mw 7.8 Kaikōura earthquake, New Zealand

2019 ◽  
Vol 52 (1) ◽  
pp. 1-22 ◽  
Author(s):  
Russ J. Van Dissen ◽  
Timothy Stahl ◽  
Andrew King ◽  
Jarg R. Pettinga ◽  
Clark Fenton ◽  
...  
Keyword(s):  
Slope Failure ◽  
Ground Deformation ◽  
Local Strain ◽  
Fault Rupture ◽  
Surface Rupture ◽  
Ground Shaking ◽  
Lateral Offset ◽  
Permanent Ground Deformation ◽  
Fault Displacement ◽  
Kaikoura Earthquake

Areas that experience permanent ground deformation in earthquakes (e.g., surface fault rupture, slope failure, and/or liquefaction) typically sustain greater damage and loss compared to areas that experience strong ground shaking alone. The 2016 Mw 7.8 Kaikōura earthquake generated ≥220 km of surface fault rupture. The amount and style of surface rupture deformation varied considerably, ranging from centimetre-scale distributed folding to metre-scale discrete rupture. About a dozen buildings – mainly residential (or residential-type) structures comprising single-storey timber-framed houses, barns and wool sheds with lightweight roofing material – were directly impacted by surface fault rupture with the severity of damage correlating with both local discrete fault displacement and local strain. However, none of these buildings collapsed. This included a house built directly atop a discrete rupture that experienced ~10 m of lateral offset. The foundation and flooring system of this structure allowed decoupling of much of the ground deformation from the superstructure thus preventing collapse. Nevertheless, buildings directly impacted by surface faulting suffered greater damage than comparable structures immediately outside the zone of surface rupture deformation. From a life-safety standpoint, all these buildings performed satisfactorily and provide insight into construction styles that could be employed to facilitate non-collapse performance resulting from surface fault rupture and, in certain instances, even post-event functionality.

scholarly journals Mineralogical and physico-chemical properties of halloysite-bearing slip surface material from a landslide during the 2018 Eastern Iburi earthquake, Hokkaido

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Jun Kameda
Keyword(s):  
Colloidal Stability ◽  
Slip Surface ◽  
High Capacity ◽  
Chemical Properties ◽  
High Mobility ◽  
Electrophoretic Analysis ◽  
Surface Material ◽  
Solution Ph ◽  
Ground Shaking ◽  
Physico Chemical

AbstractDestructive landslides were triggered by the 6.7 Mw Eastern Iburi earthquake that struck southern Hokkaido, Japan, on 6 September 2018. Heavy rainfall on 4 September in addition to intermittent rainfall around the Iburi Tobu area saturated and weakened the slope-forming materials (mostly altered volcanoclastic soils), making them susceptible to failure because of the earthquake’s strong ground motion. Most of the shallow landslides exhibited long runouts along gentle hill slopes, with characteristic halloysite-bearing slip surface at the base of the volcanic soils. This study investigated the mineralogical and physico-chemical properties of the slip surface material with the aim of understanding weakening and post-failure behaviors during the landslides. Halloysite in the slip surface had irregular-to-hollow-spherical morphology with higher mesopore volumes than tubular halloysite, which is related to a high capacity for water retention after rainfall. To reproduce possible chemical changes in the slip surface during rainfall, the sample was immersed in varying amounts of rainwater; solution pH increased and ionic strength decreased with increasing water content. These findings, alongside electrophoretic analysis, suggest that rainwater infiltration could have increased the absolute zeta potential value of the slip surface material. It is suggested that rainfall before the earthquake enhanced the colloidal stability of halloysite particles within the slip surface, owing to an increase in electrostatic repulsion. This decreased the material’s cohesive strength, which might have led to destabilization of the slope during ground shaking generated by the earthquake, and subsequent high-mobility flow after failure.

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.

Lessons Learnt from Seismic Damage Induced by the 2008 Wenchuan Earthquake

2012 ◽  
Vol 226-228 ◽  
pp. 889-896
Author(s):  
De Ping Guo ◽  
Masanori Hamada
Keyword(s):  
Wenchuan Earthquake ◽  
Slope Failure ◽  
Shear Failure ◽  
Relative Displacement ◽  
Seismic Damage ◽  
Transverse Displacement ◽  
Ground Shaking ◽  
2008 Wenchuan Earthquake ◽  
The 2008 Wenchuan Earthquake ◽  
Future Earthquake

The 2008 Wenchuan earthquake with a surface wave magnitude of 8.0 induced numerous infrastructure damages. The typical seismic damages of 61 bridges, 18 tunnels and slope reinforcements are presented. The results show longitudinal or transverse displacement was the most widespread bridge seismic damage and resulted in girder dropping, shear key failure, joint expansion and support damage. Pillar was sheared off or crushed failure due to strong motions and lack of sufficient hoop steels. Tunnel damage was mainly observed at portal, which was mostly caused by slope failure. Strong ground shaking caused multi-direction cracks in the lining, shear failure of lining resulted from serious surrounding rock relative displacement. Investigation of slope reinforcements suggests anchor cable and frame beam had good anti-seismic property. Furthermore, some suggestions about resistant countermeasures to future earthquake are proposed.

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