Landslide-dammed lake at Tangjiashan,Sichuan province,China (triggered by the Wenchuan Earthquake,May 12, 2008): risk assessment,mitigation strategy,and lessons learned

Landslides and rock avalanches triggered by the 2008 Wenchuan Earthquake produced 257 landslide dams, mainly situated along the eastern boundary of the Qinghai-Tibet Plateau where rivers descend approximately 3,000 m into the Sichuan Basin. The largest of these dams blocked the Tongkou River (a tributary of the Fujiang River) at Tangjiashan. The blockage, consisting of 2.04 × 10⁷ m³ of landslide debris, impounded a lake with a projected maximum volume of 3.15 × 10⁸ m³, potentially inundating 8.92 km² of terrain. Its creation during the rainy season and the possibility of an uncontrolled release posed a serious, impending threat to at least 1.3 million people downstream that could add substantially to the total of 69,200 individuals directly killed by the earthquake. Risk assessment of the blockage indicated that it was unlikely to collapse suddenly, and that eventual overtopping could be mitigated by notching the structure in order to create an engineered breach and achieve safe drainage of the lake. In addition to the installation of monitoring and warning instrumentation, for emergency planning we estimated several outburst scenarios equivalent to 20, 25, 33, and 50% of the dam failing suddenly, creating, respectively, 3.35, 3.84, 4.22, and 4.65 km² of flooded area, and overbank water depths of 4.6, 5.1, 5.7, and 6.2 m, respectively, in Mianyang, the second largest city in Sichuan Province, 48 km downstream from the blockage. Based on these scenarios, recommendations and plans for excavating a sluiceway, draining the lake, and downstream evacuation were proposed and later were implemented successfully, with the blockage breached by overtopping on June 10, less than a month after dam emplacement. The peak discharge of the release only slightly exceeded the flood of record at Mianyang City. No lives were lost, and significant property damage was avoided. Post-breaching evaluation reveals how future similar mitigation can be improved. Although initial breach erosion was slow, later erosion was judged uncontrollably rapid; increased slope of the engineered channel and adoption of a compound, trapezoid–triangular cross-section can be considered, as can other measures to control the rate of breach incision. Evacuees from Mianyang City spent an unnecessarily long time (12 days) in temporary settlements; more precise risk management planning can reduce this time in the future.     

Characteristics and remediation of a landslide complex triggered by the 2008 Wenchuan, China earthquake-case from Yingxiu near the earthquake epicenter

During the 2008 Wenchuan earthquake, the river valley from Yingxiu to Wenchuan experienced numerous landslides and became a prominent area of landslide complexes. The present large landslide complex near the earthquake epicenter consisted of Laohuzui slide 1, Laohuzui slide 2 and Douyaping slide. The scale, geology, morphology, sliding process, and failure mechanism of the landslide complex are analyzed by means of field investigation, aerial photograph and stereographic projection technique. Characteristics of these three slides including seismic response of slope, landslide debris, damage and potential failure are discussed: the convex slope and the upslope of fractured granitic rock at high altitude are highly prone to landsliding under earthquake; the high source altitude and long travel path determine grain sizes and the deposit angle of the slide debris; the landslide complex completely buries the G213 roadway and dams up the Minjiang River in these sections; after the earthquake, rainfall, aftershocks and river erosion may retrigger new failures, such as retrogressive slide of weathered fractured rock, colluvial landslide, debris flow, embankment failure and rockfall. The following are presented as suggested remedial measures to protect the roadway and stabilize the slope: the removing and trenching, protective concrete/rock blocks against erosion, retaining structure, rockfall stopping wall, rockfall restraining net, rock bolt, and the planting of vegetation.     

Large-Scale Variation of Solar Wind Electron Properties from Quasi-Thermal Noise Spectroscopy: Ulysses Measurements

The transport of energy in space plasmas, especially in the solar wind, is far from being understood. Measuring the temperature of the electrons and their non-thermal properties is essential to understand the transport properties in collisionless plasmas. Quasi-thermal noise spectroscopy is a reliable tool for measuring the electron temperature accurately since it is less sensitive to the spacecraft perturbations than particle detectors. We apply this method to Ulysses radio data obtained during the first pole-to-pole fast latitude scan in the high-speed solar wind, using a kappa function to describe the electron velocity distribution. We deduce the variations with heliocentric distance between 1.5 and 2.3 AU in the fast solar wind at high latitude in terms of three fitting parameters: the electron density varies as n _e??R ^?1.96±0.08, the electron temperature as T _e??R ^?0.53±0.15, and the kappa index of the distribution remains constant at ??=2.0±0.2. These observations agree with the predictions of the exospheric theory.     

相对弱势群体的城市包容性感知与影响因素分析

城市化过程中包容性价值观的缺失导致城市社会走向分化,高质量的城市化是要建设人人共享的包容城市。通过明确城市包容性感知内涵的7个维度及26个评价要素,使用2020年城市体检问卷调查数据,评价老年群体、低收入群体、低学历群体和外地人4类相对弱势群体的城市包容性感知,并检验个体属性、客观城市特征以及主观感知等因素对居民包容性感知的影响。结果发现：年龄、收入、户籍差别导致的居民包容性感知差距较大,不同学历群体的包容性感知差距较小。4类相对弱势群体的包容性感知在城市之间均存在明显差别。包容性感知因个体属性特征和城市客观特征而异,中小城市居民包容性感知显著更低,常住人口占比、住房可支付能力、人均住房面积、人口密度对于包容性感知有正向促进作用。多项要素的主观感知与包容性感知显著相关,社会治安、对弱势群体友好性、邻里关系以及综合医院的满意度是影响4类相对弱势群体包容性感知的共性因素。     

A new high-stress undrained ring-shear apparatus and its application to the 1792 Unzen–Mayuyama megaslide in Japan

Sassa and others in the Disaster Prevention Research Institute (DPRI), Kyoto University, developed a series of undrained ring-shear apparatus to physically simulate landslide initiation and motion, from DPRI-3 (Sassa 1992) to DPRI-7 (Sassa et al., Landslides 1(1):7–19, 2004). The maximum undrained capacities in the DPRI series ranged from 300 to 650 kPa. Sassa and others in the International Consortium on Landslides (ICL) have developed a new series of undrained ring-shear apparatus (ICL-1and ICL-2) for two projects of the International Programme on Landslides (IPL-161 and IPL-175). Both projects are supported by the Science and Technology Research Partnership for Sustainable Development Program (SATREPS) of Japan. ICL-1 was developed to create a compact and transportable apparatus for practical use in Croatia; one set was donated to Croatia in 2012. ICL-2 was developed in 2012–2013 to simulate the initiation and motion of megaslides of more than 100 m in thickness. The successful undrained capacity of ICL-2 is 3 MPa. This apparatus was applied to simulate possible conditions for the initiation and motion of the 1792 Unzen–Mayuyama megaslide (volume, 3.4?×?10⁸ m³; maximum depth, 400 m) triggered by an earthquake. The megaslide and resulting tsunami killed about 15,000 people. The Unzen Restoration Office of the Ministry of Land, Infrastructure and Transport (MLIT) of Japan systematically collected various papers and reports and published two summary leaflets: one in English in 2002 and an extended version in Japanese in 2003. Samples were taken from the source area (for initiation) and the moving area (for motion). The hazard area was estimated by the integrated landslide simulation model LS-RAPID, using parameters obtained with the ICL-2 undrained ring-shear apparatus. The estimated hazard area agrees reasonably with the landslide moving area reported in the Ministry leaflets.     

从北华北盆地的地质结构看1976年唐山地震的发震机理

北华北盆地经过古近纪拉张、新近纪挤压形成了怀柔—三河—唐山—锦州—下辽河向南突出的弧形构造带,它与向南推挤的南北向唐山—丰南隆起一起构成燕辽山字型构造。唐山—丰南脊柱向南推挤造成弧顶挤压应力集中。一旦应力集中超过极限值,应力必然释放,形成大地震。文章从这一认识出发对1976年唐山地震的发震机理进行了探讨。     

2006年青海玉树5.0、5.6、5.4级地震灾害损失及震害特点

2006年7月18、19日在青海玉树发生了5．0、5．6、5．4级地震,地震造成了玉树县上拉秀乡、杂多县萨呼腾镇的房屋破坏,震后青海省地震局会同玉树州地震局、玉树地震台对玉树地震的灾害损失进行了现场评估,并对玉树地震的震害特点进行了总结,最后提出了相关建议。     

内蒙白音华一号露天煤矿首采区南(非工作)帮边坡稳定性评价

根据工程地质勘察成果,分析了首采区南(非工作)帮边坡岩体的工程地质条件,并据此进行了岩石物理力学性质统计,软弱层(面)分布特征以及泥岩、炭质泥岩对地下水敏感度等研究。在此基础上建立了不同条件下不同滑面类型的边坡极限平衡法数值分析模型,并进行了相应的边坡稳定性计算成果评价,由此提出了南(非工作)帮边坡角的建议值:次边坡角采用值α1≤13°,主边坡角采用值α2≤19°。根据评价结果提出了修正岩体力学参数、合理调整采区和留设安全煤壁的建议。该评价结果为露天煤矿总平面设计系统中的边坡设计提供了依据。     

Self-Interacting Dark Matter in the SU(3)C⊗ SU(3)L ⊗ U(1)N models

We present the gauge models based on SU(3)_C⊗ SU(3)_L ⊗ U(1)_N (3-3-1) group which contain particles satisfying conditions for dark matter. There are two such models: one with exotic positive charged lepton and a variant with right-handed neutrinos. The scalar self-interacting dark matters are stable without imposing of new symmetry and should be weak-interacting. PACS Nos: 95.35.+d, 12.60.Fr, 14.80.Cp     

Regional eco-efficiency evaluation and spatial pattern analysis of the Yangtze River Economic Zone

The environmental ecology of the Yangtze River Economic Zone(YREZ) faces ecological function decline, deterioration and degradation under intense human activities, long-term development and utilization and its economy has developed rapidly over recent decades. Eco-efficiency is considered as a measure of coordinated development of economy, resources, environment and ecology, and is currently considered a very important issue. In this paper, based on the slack-based measure and data envelope analysis model, we take 129 prefecture-level cities of the YREZ as the study unit and measure the eco-efficiency of the YREZ in 2000, 2005, 2010 and 2015, which considers undesired output. The evaluation of the status quo of the regional eco-efficiency development was carried out at provincial, prefectural and city scales. The spatial autocorrelation test model and standard deviation ellipse were used to analyze the spatially distributed characteristics and the evolutionary regularity of eco-efficiency. Our study suggested that the eco-efficiency value varied significantly at different spatiotemporal scales and the overall distribution presented an "N-shaped" pattern, the value is the largest downstream and the smallest upstream. Regional eco-efficiency presented certain volatility in growth and a clear spatial positive agglomeration trend from 2000 to 2015. The spatial distribution of each agglomeration area was also significantly different, forming some high-high agglomeration areas at the center of the shaft with Shanghai and surrounding cities, and some low-low agglomeration areas at the center with middle reaches and upstream cities. The low-high over-aggregation and high-low polarization clusters were fewer. At the same time, with the change of the research period, the degree of positive agglomeration became increasingly pronounced and the eco-efficiency gap of the neighborhoodunit reduced. The regional eco-efficiency value of the YREZ presented a spatial distribution pattern in the northeast-southwest axis and the evolutionary pattern of the regional eco-efficiency similarly showed a northeast-southwest orientation.