Failure mechanisms and characteristics of the 2016 catastrophic rockslide at Su village,Lishui, China

This paper describes a recent large rockslide, which occurred at Su village in Lishui, Zhejiang Province, China, on September 28, 2016. In the past decade, a vegetation-free deformed surface was clearly visible and frequent rockfalls were noticed. Due to strong sustained rainfall, approximately 0.4 million m³ of granite blocks rapidly descended from the upper part of the hillside. The mass rushed into the V-shaped valley resulting in the formation of a barrier dam and dammed lake. The catastrophic rockslide caused 27 deaths and more than 20 houses were destroyed. The evolutionary process before the rockslide is clearly captured by high-resolution remote sensing images and photos. Video of the rockslide and field investigations show entrainment of superficial material in the middle and lower parts of the slope.     

Characteristics and numerical runout modelling of a catastrophic rock avalanche triggered by the Wenchuan earthquake in the Wenjia valley,Mianzhu, Sichuan,China

The 2008 Wenchuan earthquake triggered more than 100 rock avalanches with volumes greater than 10 million cubic metres. The rock avalanche with the longest runout amongst these destructive landslides occurred in the Wenjia valley, Mianzhu, Sichuan, China. The landslide involved the failure of about 27.5 million cubic metres of sandstone from the source area. The displaced material travelled about 4,170 m with an elevation descent of about 1,360 m, equivalent to a fahrböschung of 16.9° and covered an area of 1.5 million square metres, with the final deposited volume of approximately 49 million cubic metres. The catastrophic event destroyed the village of Yanjing, killed 48 people and buried some houses at the mouth of the Wenjia valley. On the basis of a detailed field investigation, we introduce basic characteristics of the rock avalanche and find that the rock avalanche resulted in two run-ups and a superelevation along the runout path, and downslope enlargement due to the entrainment of path materials. A numerical model (DAN3D) is used to simulate the post-failure behaviour of the rock avalanche. By means of trial and error, a combination of the frictional model and Voellmy model is found to provide the best performance in simulating this rock avalanche. The simulation results reveal that the rock avalanche had a duration of about 240 s and an average velocity of 17.4 m/s.     

Landslide hazards triggered by the 2008 Wenchuan earthquake, Sichuan, China

The 2008 Wenchuan earthquake (M _s = 8.0; epicenter located at 31.0° N, 103.4° E), with a focal depth of 19.0 km was triggered by the reactivation of the Longmenshan fault in Wenchuan County, Sichuan Province, China on 12 May 2008. This earthquake directly caused more than 15,000 geohazards in the form of landslides, rockfalls, and debris flows which resulted in about 20,000 deaths. It also caused more than 10,000 potential geohazard sites, especially for rockfalls, reflecting the susceptibility of high and steep slopes in mountainous areas affected by the earthquake. Landslide occurrence on mountain ridges and peaks indicated that seismic shaking was amplified by mountainous topography. Thirty-three of the high-risk landslide lakes with landslide dam heights greater than 10 m were classified into four levels: extremely high risk, high risk, medium risk, and low risk. The levels were created by comprehensively analyzing the capacity of landslide lakes, the height of landslide dams, and the composition and structure of materials that blocked rivers. In the epicenter area which was 300 km long and 10 km wide along the main seismic fault, there were lots of landslides triggered by the earthquake, and these landslides have a common characteristic of a discontinuous but flat sliding surface. The failure surfaces can be classified into the following three types based on their overall shape: concave, convex, and terraced. Field evidences illustrated that the vertical component of ground shaking had a significant effect on both building collapse and landslide generation. The ground motion records show that the vertical acceleration is greater than the horizontal, and the acceleration must be larger than 1.0 g in some parts along the main seismic fault. Two landslides are discussed as high speed and long runout cases. One is the Chengxi landslide in Beichuan County, and the other is the Donghekou landslide in Qingchuan County. In each case, the runout process and its impact on people and property were analyzed. The Chengxi landslide killed 1,600 people and destroyed numerous houses. The Donghekou landslide is a complex landslide–debris flow with a long runout. The debris flow scoured the bank of the Qingjiang River for a length of 2,400 m and subsequently formed a landslide dam. This landslide buried seven villages and killed more than 400 people.     

抚顺西露天矿区滑坡易发性评价与时空特征分析

近年抚顺西露天矿矿区滑坡在规模、活动频率以及空间发育位置等方面均与矿区历史滑坡呈现出较明显的时空差异性,为矿区未来治理提出新的挑战。故基于改进频率比模型,选择人类工程活动（主要是采矿工程扰动）和工程地质条件两类致灾因素,对由矿区滑坡时空差异所导致的易发性变化进行研究。结果表明：影响矿区滑坡灾害的主要因素包括坡体结构、工程岩组和水文地质条件;矿区滑坡易发性较2010年前有所降低,高易发区和较高易发区面积共减少1.294 km2,但北帮中区等地段仍呈高易发态势;滑坡易发区的空间位置与2010年前后对比发生了较大变化,矿坑西北帮滑坡易发性大幅降低,东部环矿区境界50~500 m处滑坡易发性轻微降低,北帮中段与南帮中、西段顶部滑坡易发性增加,其中北帮中段为目前最易发的区段。研究结果可为矿区闭坑停采后边坡整治及后续规划利用提供参考依据。     

川西峨眉晚古生代和中生代河流沉积中的痕迹化石群落

川西峨眉地区晚古生代和中生代地层中可识别出三种不同河流沉积环境的痕迹化石群落:(1)Scoyenia-Rhizoliths痕迹群落,产于上二叠统沙湾组,代表一种炎热潮湿气候条件下的远源曲流河沉积环境;(2)Trichichnus特化痕迹群落,发育于下三叠统飞仙关组,属近海冲积平原上时常干旱且环境条件不稳定的河流沉积环境;(3)Scoyenia-Rusophycus痕迹群落,产自上白垩统夹关组,反映经常干旱和周期性泛滥的内陆河流沉积环境.     

四川汶川Ms 8 级地震触发的典型滑坡的风险指标反演

2008年汶川大地震触发了数以万计的崩塌和滑坡,特别是沿发震断裂分布一系列大型的高速远程滑坡。为了探索地震诱发大型高速远程滑坡运动速度的反演方法,以汶川大地震典型高速远程滑坡为例,在野外调查和室内分析的基础上,结合前人的研究成果,对沿映秀－北川断裂展布的5个典型滑坡的速度进行了反演和计算。结果表明,5个滑坡的最大速度均大于50m/s,其中大光包滑坡速度最大,其下部滑体的最大速度约为300m/s,上部滑体凌空飞行的初速度高达165.6 m/s。同时,对上述滑坡的视摩擦系数进行了计算,4个滑坡的视摩擦系数介于0.16~0.4之间。这一研究的目的在于为类似地区地震滑坡的速度、最大位移量的预测和风险评估提供基础数据,对于类似地区的防灾减灾具有一定的参考价值。     

Preliminary investigation of some large landslides triggered by the 2008 Wenchuan earthquake, Sichuan Province, China

The M _s 8.0 Wenchuan earthquake or “Great Sichuan Earthquake” occurred at 14:28 p.m. local time on 12 May 2008 in Sichuan Province, China. Damage by earthquake-induced landslides was an important part of the total earthquake damage. This report presents preliminary observations on the Hongyan Resort slide located southwest of the main epicenter, shallow mountain surface failures in Xuankou village of Yingxiu Town, the Jiufengchun slide near Longmenshan Town, the Hongsong Hydro-power Station slide near Hongbai Town, the Xiaojiaqiao slide in Chaping Town, two landslides in Beichuan County-town which destroyed a large part of the town, and the Donghekou and Shibangou slides in Qingchuan County which formed the second biggest landslide lake formed in this earthquake. The influences of seismic, topographic, geologic, and hydro-geologic conditions are discussed.     

四川汶川Ms 8 级地震触发的典型滑坡的风险指标反演

2008年汶川大地震触发了数以万计的崩塌和滑坡,特别是沿发震断裂分布一系列大型的高速远程滑坡。为了探索地震诱发大型高速远程滑坡运动速度的反演方法,以汶川大地震典型高速远程滑坡为例,在野外调查和室内分析的基础上,结合前人的研究成果,对沿映秀－北川断裂展布的5个典型滑坡的速度进行了反演和计算。结果表明,5个滑坡的最大速度均大于50m/s,其中大光包滑坡速度最大,其下部滑体的最大速度约为300m/s,上部滑体凌空飞行的初速度高达165.6 m/s。同时,对上述滑坡的视摩擦系数进行了计算,4个滑坡的视摩擦系数介于0.16~0.4之间。这一研究的目的在于为类似地区地震滑坡的速度、最大位移量的预测和风险评估提供基础数据,对于类似地区的防灾减灾具有一定的参考价值。     

四川汶川Ms 8 级地震引发的滑坡与地层岩性、坡度的相关性

震后遥感影像解译与调查结果表明,在大约48678km2的区域内,汶川Ms 8.0级地震诱发了不低于48000处滑坡灾害。基于GIS的空间分析方法,使用滑坡面积百分比(LAR)与滑坡密度(LC)2个参数,对地震滑坡的空间分布与地层岩性、坡度之间的关系进行统计分析。在整个研究区范围内,滑坡面积百分比约为1.4622%,滑坡密度约为0.9862个/km2。结果表明,滑坡多发生在坡度25~50°的区域内,滑坡易发性随着坡度的增加而升高。寒武纪地层中滑坡易发性最大,LAR约10%,LC约6.5个/km2,震旦系、奥陶系和侵入岩次之,这些地层和岩石对地震滑坡的发生均是敏感的。综合分析坡度、地层岩性与滑坡空间分布的关系,结果表明,在以较破碎岩石为主的地层中,滑坡多发生在坡度小于30°的部位;在以较坚硬岩石为主的地层中,滑坡多发生在坡度大于40°的部位。     

四川汶川Ms 8 级地震引发的滑坡与地层岩性、坡度的相关性

震后遥感影像解译与调查结果表明,在大约48678km2的区域内,汶川Ms 8.0级地震诱发了不低于48000处滑坡灾害。基于GIS的空间分析方法,使用滑坡面积百分比(LAR)与滑坡密度(LC)2个参数,对地震滑坡的空间分布与地层岩性、坡度之间的关系进行统计分析。在整个研究区范围内,滑坡面积百分比约为1.4622%,滑坡密度约为0.9862个/km2。结果表明,滑坡多发生在坡度25~50°的区域内,滑坡易发性随着坡度的增加而升高。寒武纪地层中滑坡易发性最大,LAR约10%,LC约6.5个/km2,震旦系、奥陶系和侵入岩次之,这些地层和岩石对地震滑坡的发生均是敏感的。综合分析坡度、地层岩性与滑坡空间分布的关系,结果表明,在以较破碎岩石为主的地层中,滑坡多发生在坡度小于30°的部位;在以较坚硬岩石为主的地层中,滑坡多发生在坡度大于40°的部位。     

Dynamics of the Niumiangou Creek rock avalanche triggered by 2008 Ms 8.0 Wenchuan earthquake, Sichuan, China

The Niumiangou Creek rock avalanche was triggered by an M_s 8.0 earthquake that happened on 12 May 2008 in the Sichuan Province, China. The rock avalanche traveled a horizontal distance of 3.0 km over a vertical elevation difference of 0.89 km, equivalent to a coefficient of friction of only 0.29. The travel path of the rock avalanche can be divided into three segments: (1) failing and disintegrating, (2) flying, (3) flowing. In the failing and disintegrating segment, the rock slope failed because of the coupled action of horizontal and vertical force of the earthquake, then smashed into the opposite mountain and disintegrated. In the flying segment, the disintegrating rock mass changed direction and flew into the Lianhuaxin Creek, which was different from the previous research results that concluded rock debris flowed in Lianhuaxin Creek. A great amount of air trapped and compressed under the rock debris acted as air cushion and supported the rock debris to fly a further distance. In the flowing segment, the rock debris flowed on the ground surface in Niumiangou Creek. The flowing velocity has been estimated from the maximum elevation and runup according to the damaged trimlines of the debris. The saturated fine material in Niumiangou Creek entrained by the failed debris mass is thought to have contributed to the long runout of the debris. The Niumiangou Creek rock avalanche is one of the three longest rock avalanches triggered by Wenchuan earthquake. The conclusions of the paper have implications for hazard assessment of potential rock avalanches in the earthquake area and the other similar mountainous area in west China.     

Mechanism of the catastrophic June 2017 landslide at Xinmo Village,Songping River,Sichuan Province,China

On June 24, 2017, a catastrophic landslide (Xinmo landslide) occurred on the left bank of Songping river in Diexi town, Sichuan Province, China. Based on field investigations, this paper tries to reveal the cause and mechanism of the initiation and development of the Xinmo landslide. Xinmo landslide is located in the so called “Minshan block.” This tectonic block is very active and generates many earthquakes. Among them, the 1933 Diexi Ms 7.5 earthquake which had an indispensable effect on the occurrence of the Xinmo landslide, whose distance to the recent Xinmo landslide is only 8.7 km. The 1933 earthquake triggered the collapse of the Qianxin gully, which damaged the rock mass forming the source of the Xinmo landslide and creating a free prominent ridge. The later 1976 Songpan Ms 7.2 earthquake and the 2008 Wenchuan Ms 8.0 earthquake further damaged the integrity of the rock mass in the source area of the 2017 Xinmo landslide. The Xinmo landslide developed on a typical bedding dip slope with metasandstone intercalated with a few thin bedded slate layers. The slate intercalation gives the slope a very low shear strength in the dip direction and the long term rainfall may have softened the slip zone and the locked section. These two aspects have promoted the occurrence of Xinmo landslide.     

Correction to: The catastrophic landside in Maoxian County,Sichuan, SW China,on June 24, 2017

Natural Hazards - Due to an oversight, four references were cited incorrectly in the reference list of the original publication as well as in the text of the publication. The first names were used...     

川东北飞仙关组白云岩的主要类型、地球化学特征和白云化机制

四川盆地东北部蕴藏有丰富的烃类资源,三叠系飞仙关组的白云岩是最主要的储层和产层,这使得飞仙关组白云岩成为人们近年来高度关注的对象.按照结构,我们可以将飞仙关组白云岩分为三种端元类型:微晶白云岩、具原始结构的粒屑白云岩和结晶白云岩,在一个向上变浅的剖面旋回中,这三种白云岩分别位于旋回的顶部、上部和中下部.微晶白云岩和具原始结构的粒屑白云岩具有较高的锰含量和较低的包裹体均一化温度,白云化流体的δ~(18O) 值(从白云石的包裹体均一化温度和δ~(18O) 值反演,以下同)介于大气水和海水之间,反映这类白云岩形成于有大气水参与的相对开放的沉积-成岩环境中,蒸发泵作用(对于微晶白云岩)和混合水作用(对于具原始结构的粒屑白云岩)可能是其主要的形成机制;结晶白云岩(表现为好储层)具有很低的锰含量和较高的包裹体均一化温度,白云化流体的δ~(18O) 值显著高于早三叠世海水,表明这类白云岩形成于相对封闭的埋藏成岩环境,白云化流体具较高的温度和盐度,但到目前为止,还没有一个已有模式可以较好地解释这类白云岩的成因.     

四川雷波峨眉山玄武岩岩石学及地球化学特征

以剖面测量及野外系统观察、显微镜下及地球化学研究为基础,认为雷波地区峨眉山玄武岩主要具有以下特点:①岩石类型主要为致密块状玄武岩、斑状玄武岩、杏仁状玄武岩,发育柱状节理,为典型陆相喷发玄武岩;②岩石化学分类为碱性玄武岩,具高钛特征,为板内拉张玄武岩;③玄武岩经历了相似的岩浆演化和结晶分异,形成深度大,起源于富集地幔源,是地幔柱作用的产物;④玄武岩是攀西裂谷拉张作用的产物,无爆发角砾岩相,主要为喷溢-溢流相,可能属攀西裂谷的边缘相带。     

Environmental geochemistry and ecological risk of vanadium pollution in Panzhihua mining and smelting area, Sichuan, China

1 Introduction Vanadium (V) is a relatively abundant elemenwhich is widely distributed in nature; howeverworkable V deposits are very rare (World HealthOrganization, 2001). Vanadium is a trace elementwhich may be beneficial and possibly essential fohuman…     

Characteristics,mechanisms, and post-disaster lessons of the delayed semi-diagenetic landslide in Hanyuan,Sichuan, China

Landslides following rainfall occurrence are a widespread phenomenon. The neglect of this phenomenon leads to serious loss of life when disasters occur. At 03:45 (GMT?+?8) on August 21, 2020, a semi-diagenetic landslide occurred in Zhonghai Village, Hanyuan County, China, which occurred 42 h after earlier rainfall. Nine people privately returned to their homes after evacuation of the dangerous area. In this disaster, eight people were lost and one injured. This study explores the failure characteristics, inducement, and mechanisms of the landslide via field investigations, resident interviews, multi-temporal images, field drilling, and geotechnical tests. Hydrological numerical calculations were also performed to uncover the seepage and transfer processes of the groundwater in the slope. Finally, problems in the current community early warning system were analyzed and corresponding suggestions put forward. The results show that the maximum sliding depth of the landslide was 27.5 m, the total area was 80,000 m², and the sliding volume was about 58,0000 m³, making it a medium-sized deep landslide. In addition to the vertical seepage of rainfall in the landslide area, the downward movement of rainfall in the back and upper catchment areas along the silt sand strata also affected the stability of the landslide. More needs to be done to make the population aware of this lag phenomenon to achieve scientific disaster reduction. This study not only provides a case study of a lagging semi-diagenetic landslide, but also provides insight into hydrological boundary determination and landslide early warning system construction.

     

四川峨眉晚侏罗世湖泊沉积中震积岩的发现及其意义

四川峨眉川主乡上侏罗统的震积岩由微型断裂层、微型褶皱层、碎块层、均一层组成,总厚0.69m.上覆和下伏地层皆为受地震影响的、水平层理保存完好的未震动层.上述自下而上的震积岩层序特征,反映了地震震波对水和沉积界面以下的沉积物因压实作用不同和变形能力差异而形成的不同沉积构造.