scholarly journals Contributing factors to the failure of an unusually large landslide triggered by the 2014 Ludian, Yunnan, China, <i>M</i><sub>s</sub>  =  6.5 earthquake

2016 ◽  
Vol 16 (2) ◽  
pp. 497-507 ◽  
Author(s):  
Z. F. Chang ◽  
X. L. Chen ◽  
X. W. An ◽  
J. W. Cui
Keyword(s):  
Crustal Deformation ◽  
Landslide Dam ◽  
Debris Avalanche ◽  
Contributing Factors ◽  
Ground Shaking ◽  
Field Investigations ◽  
Rock Structure ◽  
Large Landslide ◽  
Weak Interlayer ◽  
Steep Slopes

Abstract. The 3 August 2014 Ludian, China, Ms  =  6.5 earthquake caused many large landslides. The biggest occurred at Hongshiyan near the epicenter, had a volume of 1.0  ×  107 m3 and dammed the Niulanjiang River, creating a large lake. Post-event field investigations yielded detailed data on the following aspects: rock structure of the landslide, the local lithology and geometry of the area around the landslide dam and composition and grain sizes of the debris avalanche. Based on these data, this work analyzes the geology and topography of the Hongshiyan area, and explores reasons for the occurrence of an unusually large landslide at this location. Our analysis suggests the following conditions are responsible for this catastrophic event. (1) Due to recent crustal deformation, intense incision on the river increased topographic relief with steep slopes and scarps. (2) Combined structures, including unloading fissures, high-angle joints and low-angle beds along the river, as well as an upper-strong and lower-weak interlayer structure on the slope, especially the existence of weak layers in the slope, are important factors that contribute to this large failure. (3) Hongshiyan lies near an active fault, where intense crustal deformation has resulted in rock fractures and weathering, and frequent earthquakes may progressively reduce the strength of the slope. (4) During the Ms  =  6.5 earthquake, the terrain and site conditions led to abnormally strong ground shaking. The combined impacts of these factors triggered a very large landslide during a moderate-sized earthquake.

scholarly journals Why the 2014 Ludian, Yunnan, China <i>M</i><sub>s</sub> 6.5 earthquake triggered an unusually large landslide?

2015 ◽  
Vol 3 (1) ◽  
pp. 367-399 ◽  
Author(s):  
Z. F. Chang ◽  
X. L. Chen ◽  
X. W. An ◽  
J. W. Cui
Keyword(s):  
Active Fault ◽  
Rock Fractures ◽  
Catastrophic Event ◽  
Grain Sizes ◽  
Field Investigations ◽  
Rock Structure ◽  
Large Landslide ◽  
Steep Slopes ◽  
Topographic Relief ◽  
Strong Ground

Abstract. The 3 August 2014 Ludian, China Ms 6.5 earthquake has spawned a mass of severe landslides. Of them the biggest occurred at Hongshiyan near the epicenter, which has 1200 × 104 m3, clogging the Niulanjiang River, and creating a large dammed lake. Post-event field investigations yield detailed data on following aspects: rock structure of landslides, lithology, and geometry of the dam, composition and grain sizes of debris avalanches. Based on these data, this work further analyzes the geology and topography of the Hongshiyan area, and explores the mechanism for occurrence of such an unusual big landslide at this place. Our analysis suggests the following conditions are responsible for this catastrophic event: (1) during the Ms 6.5 earthquake, the special terrain and site conditions led to abnormally strong ground shake. (2) Hongshiyan lies nearby an active fault, where intense crustal deformation resulted in rock fractures and weathering. (3) Intense incision on the river increased topographic relief with steep slopes and scarps. (4) Combined structures, including unloading fissures, high-angle joints and low-angle beds along the river as well as upper-tough and lower-soft structure on the slopes. It is the joint functions of these conditions that triggered such seldom seen landslides during a moderated-sized earthquake.

scholarly journals Geomorphic effects of recurrent outburst superfloods in the Yigong River on the southeastern margin of Tibet

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kaiheng Hu ◽  
Chaohua Wu ◽  
Li Wei ◽  
Xiaopeng Zhang ◽  
Qiyuan Zhang ◽  
...  
Keyword(s):  
Landslide Dam ◽  
Upstream Migration ◽  
One Dimensional ◽  
Landform Evolution ◽  
Outburst Floods ◽  
Stepwise Method ◽  
Large Landslide ◽  
Southeastern Margin ◽  
Channel Slope ◽  
The One

AbstractLandslide dam outburst floods have a significant impact on landform evolution in high mountainous areas. Historic landslide dams on the Yigong River, southeastern Tibet, generated two outburst superfloods > 105 m3/s in 1902 and 2000 AD. One of the slackwater deposits, which was newly found immediately downstream of the historic dams, has been dated to 7 ka BP. The one-dimensional backwater stepwise method gives an estimate of 225,000 m3/s for the peak flow related to the paleo-stage indicator of 7 ka BP. The recurrence of at least three large landslide dam impoundments and super-outburst floods at the exit of Yigong Lake during the Holocene greatly changed the morphology of the Yigong River. More than 0.26 billion m3 of sediment has been aggraded in the dammed lake while the landslide sediment doubles the channel slope behind the dam. Repeated landslide damming may be a persistent source of outburst floods and impede the upstream migration of river knickpoints in the southeastern margin of Tibet.

Visible geological effects of the CANNIKIN event

1972 ◽  
Vol 62 (6) ◽  
pp. 1519-1526 ◽  
Author(s):  
R. H. Morris ◽  
L. M. Gard ◽  
R. P. Snyder
Keyword(s):  
Vertical Displacement ◽  
Ground Zero ◽  
Subsidence Area ◽  
Collapse Time ◽  
Field Investigations ◽  
Principal Directions ◽  
Two Stages ◽  
Steep Slopes ◽  
Rock Slides ◽  
Lake Beds

abstract Postshot field investigations indicate that most of the visible geological effects produced by the CANNIKIN event are limited to an area of a 2-km radius from ground zero (GZ). Two stages of fracturing are recognized, one at shot time that induced a maximum of 0.6 m vertical displacement along the Teal Creek Fault located 1,070 m northwest of GZ, and one inferred to have occurred at collapse time (38 hr later). The three principal directions of fractures are east-northeast, northwest, and north and are related to pre-existing faults and lineaments. Major displacement along a fault located 760 m southeast of GZ is inferred to have occurred during collapse. Preliminary surveys indicate that the collapse sink is asymmetric with relation to GZ. The oval subsidence area is 1,270 by 915 m and the surface low, located 366 m southeast of GZ, subsided about 20 m. Several lakes are forming in the sink area. A portion of the intertidal platform along the Bering coast was uplifted about 1 m and major rock slides occurred along the cliffs within this zone of uplift. Elsewhere, minor rockfalls, slides and tundra slumps occurred along cliffs or steep slopes. Lake beds have been fractured and, in some cases, the lakes have drained.

scholarly journals A large landslide in Zigui County, Three Gorges area

2004 ◽  
Vol 41 (6) ◽  
pp. 1233-1240 ◽  
Author(s):  
F C Dai ◽  
J H Deng ◽  
L G Tham ◽  
K T Law ◽  
C F Lee
Keyword(s):  
Clayey Soil ◽  
Landslide Dam ◽  
Bedding Plane ◽  
Raw Material ◽  
Left Bank ◽  
Three Gorges ◽  
Shear Surface ◽  
Three Gorges Area ◽  
Dam Breaching ◽  
Large Landslide

On 13 July 2003, a landslide with a volume of approximately 20 × 106 m3 occurred on the left bank of the Qinggan River, Zigui County, Hubei Province, China. As a result, 14 people died and 10 people are missing. A landslide dam was formed, blocking the Qinggan River. A channelized diversion was constructed for prevention of upstream flooding and damage downstream caused by dam breaching. The landslide was a typical translational rockslide in weathered shale and sandstone, a block of which slipped down along the bedding plane. It is estimated that the landslide was caused by the combined effect of the following factors: (i) a bedding plane between incompetent weathered shale and competent sandstone that daylights at or is shallowly buried at the bottom of the Qinggan River; (ii) a thin layer of clayey soil acting as the slip plane that is likely a preexisting shear surface; (iii) excavation of the shale as raw material for brick fabricating on the slope; and (iv) a combination of prolonged rainfall and reservoir impounding.Key words: landslide, landslide dam, rainfall, impounding, Three Gorges area.

Bedload-to-suspended load ratio and rapid bedrock incision from Himalayan Landslide-dam lake record

2007 ◽  
Vol 68 (1) ◽  
pp. 111-120 ◽  
Author(s):  
Beth Pratt-Sitaula ◽  
Michelle Garde ◽  
Douglas W. Burbank ◽  
Michael Oskin ◽  
Arjun Heimsath ◽  
...  
Keyword(s):  
Landslide Dam ◽  
Load Ratio ◽  
Suspended Load ◽  
Sediment Flux ◽  
Mountain River ◽  
Central Nepal ◽  
Large Landslide ◽  
Significant Addition ◽  
Lake Record

AbstractAbout 5400 cal yr BP, a large landslide formed a > 400-m-tall dam in the upper Marsyandi River, central Nepal. The resulting lacustrine and deltaic deposits stretched > 7 km upstream, reaching a thickness of 120 m. 14C dating of 7 wood fragments reveals that the aggradation and subsequent incision occurred remarkably quickly (∼ 500 yr). Reconstructed volumes of lacustrine (∼ 0.16 km3) and deltaic (∼ 0.09 km3) deposits indicate a bedload-to-suspended load ratio of 1:2, considerably higher than the ≤ 1:10 that is commonly assumed. At the downstream end of the landslide dam, the river incised a new channel through ≥ 70 m of Greater Himalayan gneiss, requiring a minimum bedrock incision rate of 13 mm/yr over last 5400 yr. The majority of incision presumably occurred over a fraction of this time, suggesting much higher rates. The high bedload ratio from such an energetic mountain river is a particularly significant addition to our knowledge of sediment flux in orogenic environments.

The Effects of Building Characteristics and Site Conditions on the Damage Distribution in Boumerdès after the 2003 Algeria Earthquake

2012 ◽  
Vol 28 (1) ◽  
pp. 185-216 ◽  
Author(s):  
Abdelghani Meslem ◽  
Fumio Yamazaki ◽  
Yoshihisa Maruyama ◽  
Djillali Benouar ◽  
Abderrahmane Kibboua ◽  
...  
Keyword(s):  
Structural Characteristics ◽  
Free Field ◽  
Contributing Factors ◽  
Damage Distribution ◽  
Moment Frame ◽  
Field Investigations ◽  
Algerian Seismic Code ◽  
Frame Systems ◽  
Observed Damage ◽  
River Valleys

This study highlights the major contributing factors to the observed damage distribution in the city of Boumerdès after the 2003 Algeria earthquake. The results of field investigations and statistical analyses show that a majority of the damaged buildings, mostly mid-rise reinforced concrete (RC) moment-frame systems, were located on steep slopes and small hilltops, along river valleys. The horizontal-to-vertical (H/V) ratios from free-field microtremor measurements at these sites did not show clear results. In contrast, buildings with the same structural characteristics located on flat ground did not suffer much damage, and clear peaks were observed from the H/V ratio curves. The amplification effects of topography have not been incorporated into the revised Algerian seismic code, but the results from this study show the importance of considering this factor when designing new buildings for earthquake resistance.

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

&lt;p&gt;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.&amp;#160;However, liquefaction&amp;#8217;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.&lt;/p&gt;&lt;p&gt;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&amp;#8217;s long reach. Soon after the slide event, we mapped more than 350 sand boils &amp;#8211; classic indicators of liquefaction &amp;#8211; 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.&lt;/p&gt;&lt;p&gt;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.&lt;/p&gt;

Observations from the large, rapid Yigong rock slide – debris avalanche, southeast Tibet

2012 ◽  
Vol 49 (5) ◽  
pp. 589-606 ◽  
Author(s):  
Qiang Xu ◽  
Yanjun Shang ◽  
Theo van Asch ◽  
Shitian Wang ◽  
Zhuoyuan Zhang ◽  
...  
Keyword(s):  
High Speed ◽  
Landslide Dam ◽  
Debris Avalanche ◽  
Dam Failure ◽  
Excess Pore Pressure ◽  
Rock Slide ◽  
Long Run ◽  
Landslide Event ◽  
Slide Debris ◽  
Sand Boils

The Yigong rock slide – debris avalanche (YRA), which occurred on 9 April 2000, received worldwide attention as one of the largest nonseismic landslides in recent years, with a volume of 0.3 × 109 m3. Sixty-two days after this landslide event, a catastrophic flood happened because of landslide dam failure. One of the special features of this debris avalanche is liquefaction, which plays an important role in the entrainment and long run-out distance and high-speed movement of the debris avalanche. Numerous sand boils were found in the deposition zone, providing strong evidence for liquefaction. The YRA provides the first actual evidence for a theoretical model where the mechanisms of excess pore pressure and liquefaction induced by undrained loading, and entrainment and dissipation control the run out and deposition of the debris avalanche. The damage mode to trees and the presence of debris cones or molards with a rounded top is proven to be the result of strong air waves and eddies. These features all imply that the YRA is a solid–liquid–air mixed-debris avalanche.

scholarly journals Landslides caused by the Mw7.8 Kaikōura earthquake and the immediate response

2017 ◽  
Vol 50 (2) ◽  
pp. 106-116 ◽  
Author(s):  
Sally Dellow ◽  
Chris Massey ◽  
Simon Cox ◽  
Garth Archibald ◽  
John Begg ◽  
...  
Keyword(s):  
Ground Surface ◽  
Landslide Dam ◽  
Material Strength ◽  
Fault Rupture ◽  
The South ◽  
Main Trunk ◽  
Ground Shaking ◽  
Landslide Dams ◽  
Kaikoura Earthquake ◽  
First Time

Tens of thousands of landslides were generated over 10,000 km2 of North Canterbury and Marlborough as a consequence of the 14 November 2016, Mw7.8 Kaikōura Earthquake. The most intense landslide damage was concentrated in 3500 km2 around the areas of fault rupture. Given the sparsely populated area affected by landslides, only a few homes were impacted and there were no recorded deaths due to landslides. Landslides caused major disruption with all road and rail links with Kaikōura being severed. The landslides affecting State Highway 1 (the main road link in the South Island of New Zealand) and the South Island main trunk railway extended from Ward in Marlborough all the way to the south of Oaro in North Canterbury. The majority of landslides occurred in two geological and geotechnically distinct materials reflective of the dominant rock types in the affected area. In the Neogene sedimentary rocks (sandstones, limestones and siltstones) of the Hurunui District, North Canterbury and around Cape Campbell in Marlborough, first-time and reactivated rock-slides and rock-block slides were the dominant landslide type. These rocks also tend to have rock material strength values in the range of 5-20 MPa. In the Torlesse ‘basement’ rocks (greywacke sandstones and argillite) of the Kaikōura Ranges, first-time rock and debris avalanches were the dominant landslide type. These rocks tend to have material strength values in the range of 20-50 MPa. A feature of this earthquake is the large number (more than 200) of valley blocking landslides it generated. This was partly due to the steep and confined slopes in the area and the widely distributed strong ground shaking. The largest landslide dam has an approximate volume of 12(±2) M m3 and the debris from this travelled about 2.7 km2 downslope where it formed a dam blocking the Hapuku River. The long-term stability of cracked slopes and landslide dams from future strong earthquakes and large rainstorms are an ongoing concern to central and local government agencies responsible for rebuilding homes and infrastructure. A particular concern is the potential for debris floods to affect downstream assets and infrastructure should some of the landslide dams breach catastrophically. At least twenty-one faults ruptured to the ground surface or sea floor, with these surface ruptures extending from the Emu Plain in North Canterbury to offshore of Cape Campbell in Marlborough. The mapped landslide distribution reflects the complexity of the earthquake rupture. Landslides are distributed across a broad area of intense ground shaking reflective of the elongate area affected by fault rupture, and are not clustered around the earthquake epicentre. The largest landslides triggered by the earthquake are located either on or adjacent to faults that ruptured to the ground surface. Surface faults may provide a plane of weakness or hydrological discontinuity and adversely oriented surface faults may be indicative of the location of future large landslides. Their location appears to have a strong structural geological control. Initial results from our landslide investigations suggest predictive models relying only on ground-shaking estimates underestimate the number and size of the largest landslides that occurred.

Geomorphic processes and risk related to a large landslide dam in a highly urbanized Mediterranean catchment (Genova, Italy)

Geomorphology ◽  
2019 ◽  
Vol 327 ◽  
pp. 48-61 ◽  
Author(s):  
G. Paliaga ◽  
F. Faccini ◽  
F. Luino ◽  
L. Turconi ◽  
P. Bobrowsky
Keyword(s):  
Landslide Dam ◽  
Large Landslide ◽  
Geomorphic Processes
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