基于历史地震数据的地震烈度与人员死亡率相关性研究

基于历史震例数据,通过对不同烈度的人员死亡率的分析发现,人员死亡率与地震烈度存在着正相关关系,即人员死亡率随烈度的增加而增大,不同烈度的人员死亡率有各自的分布区间范围,而通过对相邻烈度的人员死亡率的分析发现,相邻烈度人员死亡率存在着1个数量级的倍数关系,一般在10倍左右,在低烈度区域,倍数关系集中于偏向大于10倍的区间范围;在高烈度区域,倍数关系集中于小于10倍的区间范围。在此结果上,基于地震烈度、震级等因素构建了烈度人员死亡率模型,决定系数R²值为0.8667,拟合结果相对较好,能够为后续基于分烈度人员死亡率的地震人员死亡评估模型提供参考。     

2021年西藏比如6.1级地震前重力变化特征研究

利用青藏高原地区2015—2020年期间流动重力观测资料,研究2021年3月19日比如6.1级地震前重力变化特征,结果表明:①本次地震前约3年的重力图像中出现穿过震中区的SN向重力变化梯度带,其形态和持续时间与现有典型指标一致,表明重力变化较为清晰地反映了本次地震孕育过程中所引起的重力异常信号;②实测重力场变化与正断型断层位错引起的重力变化在形态上基本一致,结合本次比如6.1级地震的震源机制以正断为主,推测羌塘块体EW向拉伸运动为本次地震的发震背景。     

Effect of tamping interval on consolidation of dredged slurry using vacuum preloading combined with dynamic consolidation

The effect of combining vacuum preloading and low-energy dynamic consolidation is predominantly controlled by the tamping interval time. It is, therefore, imperative to identify a suitable parameter and optimise the tamping interval time. In this study, the effect of the tamping interval time on the consolidation of slurries was investigated by conducting laboratory model tests. Consequently, various tamping interval times were obtained by controlling the dissipation of pore water pressure at different levels of 20%, 40%, 60%, 80%, and 100% to determine the optimal interval time. In terms of surface settlement variation, dissipation of pore water pressure, and distributions of the water content and shear strength variation profile, it was shown that a rubber soil state was reached at a dissipation rate of 20% pore water pressure. When the tamping interval time was set to a dissipation rate of 80% pore water pressure, the consolidation effect was optimal.

     

西秦岭甘青交界一带晚三叠世火山岩岩石成因及构造指示意义

西秦岭甘肃、青海交界一带中生代火山岩较为发育,火山岩组成以安山质、流纹质为主,均为高钾钙碱性火山岩,主、微量元素含量变化较大。SiO2的质量分数为5667%～7817%,平均6978%, Al2O3含量较高(1277%～1729%,平均1464%)。TiO2含量少(002％～075%,平均022%),Na2O/K2O比值较小(003％～268%,平均065%)。轻稀土元素中等富集,重稀土元素相对亏损,稀土元素配分曲线明显右倾,具Eu负异常。安山质火山岩与流纹质火山岩稀土元素球粒陨石配分曲线中重稀土型式明显不同,暗示二者来自不同的源区。微量元素中P、Nb、Ti、Ta等高场强元素(HFS)相对亏损,Th、 Ba、K、Rb等大离子亲石元素相对富集。研究区安山岩LA ICP MS锆石U Pb同位素定年结果为(236±12)Ma,代表了火山岩的喷发年龄。它们形成于隆务峡蛇绿岩洋壳向南俯冲的活动大陆边缘弧环境,为俯冲洋壳在地幔深部发生高程度部分熔融作用的产物,并在上升过程中受到陆壳物质作用。在岩浆演化过程受部分熔融和分异结晶作用的控制,但安山质火山岩主要受控于分异结晶作用,而流纹质火山岩受部分熔融作用较大。     

Integration of multi-parametric fuzzy analytic hierarchy process and GIS along the UNESCO World Heritage: a flood hazard index,Mombasa County,Kenya

Natural Hazards - Flood is a natural hazard affecting human life and ecosystem globally causing catastrophic disasters. Most flood-induced socioeconomic losses are exacerbated by unabated urban...     

Quantitative assessment of the impact of an inter-basin surface-water transfer project on the groundwater flow and groundwater-dependent eco-environment in an oasis in arid northwestern China

Inter-basin water transfer projects (IBWTPs) can involve basins as water donors and water receivers. In contrast to most studies on IBWTPs, which mainly impact the surface-water eco-environment, this study focuses on the impacts of an IBWTP on groundwater and its eco-environment in a water donor basin in an arid area, where surface water and groundwater are exchanged. Surface water is assumed to recharge groundwater and a groundwater numerical simulation model was constructed using MODFLOW. The model was used to quantitatively evaluate the impact of an IBWTP located in the upstream portion of Nalenggele River (the biggest river in the Qaidam basin, Northwest China). The impact involved decrease in spring flow, drawdown of groundwater, reduction in oasis area, and an increase in species replacement of oasis vegetation in the midstream and downstream of the river. Results show that the emergence sites of springs at the front of the oasis will move 2–5 km downstream, and the outflow of springs will decrease by 42 million m³/a. The maximum drawdown of groundwater level at the front of the oasis will be 3.6 m and the area across which groundwater drawdown exceeds 2.0 m will be about 59.02 km², accounting for 2.71% of the total area of the oasis. Under such conditions, reeds will gradually be replaced by Tamarix, shrubs, and other alternative plant species. These findings have important implications for the optimization of water resource allocation and protection of the eco-environment in arid regions.     

A disaggregation approach for estimating high spatial resolution broadband emissivity for bare soils from Landsat surface reflectance

High spatial resolution land surface broadband emissivity (BBE) is not only useful for surface energy balance studies at local scales, but also can bridge the gap between existing coarser resolution BBE products and point-based field measurements. This study proposes a disaggregation approach that utilizes the established BBE–reflectance relationship for estimating high spatial resolution BBE for bare soils from Landsat surface reflectance data. The disaggregated BBE is compared to the BBE calculated from spatial–temporal matched Advanced Spaceborne Thermal Emission and Reflectance Radiometer emissivity product. Comparison results show that better agreement is achieved over relative homogeneous areas, but deteriorated over heterogeneous and cloud-contaminated areas. In addition, field-measured emissivity data over large homogeneous desert were also used to validate the disaggregated BBE, and the bias is 0.005. The comparison and validation results indicated that the disaggregation approach can obtain high spatial resolution BBE with better accuracy for homogeneous area.     

运用定量化结构分析方法揭示蚀变花岗斑岩的形成过程——以新疆莫阿特茂金岩体为例

地球化学分析方法已广泛运用于火成岩成因的研究中,但对于一些蚀变较严重的岩石,有时仅通过地球化学分析难以还原岩浆固结的过程。火成岩定量化结构分析方法是通过对岩石中矿物的定量分析(诸如晶体粒度分布分析,晶体空间分布分析,以及晶体定向程度分析等),从而反演岩浆固结过程中发生的动力学过程。这种方法很好地避免了蚀变作用对还原岩体形成过程所产生的诸多影响。本文运用火成岩定量化结构分析方法,对新疆莫阿特茂金花岗斑岩体钻孔中10个样品的钾长石斑晶和石英斑晶分别进行分析。尽管这些样品普遍发生了碳酸盐化蚀变作用,定性观察中结构特征也比较均一,但是钾长石和石英斑晶的定量化结构数据及其在钻孔深度(约170 m)范围内的变化趋势显示,茂金花岗斑岩体可能至少由4次脉冲岩浆叠加形成,每股岩浆中心的CSD曲线小晶体缺乏,发生了粗化现象。由于脉冲式岩浆多次注入,导致的温度振荡加剧了矿物粗化。脉冲岩浆中心处斑晶体积含量的增加,可能与岩浆流动过程中对大晶体的影响有关,80 m深度以下脉冲岩浆接触带的斑晶体积含量明显增加,是由于机械压缩导致的。     

Study on the geological conditions of metallogenesis of the Shazi large-scale anatase deposit in Qinglong County,Guizhou Province

The Shazi large-scale anatase deposit in Qinglong County, Guizhou Province, has been discovered recently and now is under exploration. Investigations show that the orebodies mostly occur at the top of the karst unconformity of the Middle Permian Maokou Formation strata and at the bottom of the Emeishan basalt. And the following three prerequisites should be satisfied for the formation of the deposit： 1） there must be the material source of anatase; 2） there must be weekly alkaline media and low-tempeature and low-pressure conditions; 3） there was no high-temperature and high-pressure environment subsequently for the transformation of anatase into rutile. In the Emeishan basalt of western Guizhou, the element Ti mostly entered the silicon-oxygen tetrahedra of picrite in heterovalent isomorphism （Ti4＋＋Al3＋→Mg2＋＋Si4＋）. When volcanic ejecta resultant from strong eruption of the Emeishan basalt magma fell into water, picrite was usually dissociated to chlorite. Thus, the element Ti4＋ in the picrite could be released from the silicon-oxygen tetrahedraa of picrite into water, and conbined with oxygen in the water to form TiO2. This paper has proved that this deposit, enriched in anatase, discovered recently at Shazi, Qinglong Country, Guizhou Province, is a residual-deluvial-type deposit. Its genesis can be explained as follows. Volcanic clastics formed at the early stage of strong eruption of the Emeishan basalt magma were chemically deposited to form anatase in the low-temperature, low-pressure and weekly alkaline waters in the karst depressions at the top of the Maokou Formation （limestone） strata. The anatase was then dissociated owing to weathering and leaching during the Quaternary and the anatase was further enriched to form the residual-deluvial-type anatase ore deposit.