Field-based description of near-surface crustal deformation in a high-strain shear zone: A case study in southern Kyushu,Japan     

Masakazu Niwa  Koji Shimada  Shuji Terusawa  Akira Goto  Nariaki Nishiyama  Toru Nakajima  Takanori Ishihara  Hiroaki Hakoiwa 《Island Arc》2024,33(1):e12516

This study investigated geological evidence for near-surface crustal deformation in a high-strain shear zone that has been geodetically identified but which is not associated with obvious tectonic landforms. Fieldwork was conducted in the east–west-trending southern Kyushu high-strain shear zone (SKHZ), Japan, focusing mainly on occurrences of fracture zones, which are defined by a visible fracture density of >1 per 10 cm² and are commonly associated with cataclasite, fault breccia, and gouge. The area in which east–west-trending fracture zones are dominant is restricted to the east–west-trending, ~2-km-wide aftershock area of the 1997 Northwestern Kagoshima Earthquakes. Analysis of slip data from minor faults using the multiple inverse method, irrespective of whether the faults are in fracture zones, reveals that the area where the calculated main stress field is consistent with the current stress field estimated from focal-mechanism solutions of microearthquakes is restricted to the east–west-trending aftershock area. This finding for the SKHZ contrasts with the case of the Niigata–Kobe Tectonic Zone, which is a major strain-concentration zone with many exposed active faults in central Japan and for which the stress field estimated using fault-slip data is considered to be uniform and coincides with the current stress field. The cumulative amount of displacement estimated from the areal density of fracture zones in the SKHZ study area is smaller than that estimated from geodetically measured strain rates. Investigations based on slip data from minor faults and fracture-zone occurrence could help to identify concealed faults that are too small to generate tectonic landforms but which are sufficiently large to trigger major earthquakes.  相似文献   

天津市海洋灾害及其影响分析   总被引：4，自引：0，他引：4  

马振兴 《海洋通报》2006,25(2):41-45,54

根据主要致灾因子,将天津市沿海海洋灾害分为水文气象灾害、海洋地质灾害和海洋环境灾害3大类型,并在统计资料分析的基础上,综合归纳出天津市海洋灾害具有发生频繁和损失严重,以及致灾因子和各灾害间关系复杂的基本特点;从地理位置、地形、气象、天文潮因素和全球海平面上升、区域构造沉降、沉积物压实、人为地面沉降因素,以及海区生物、环境、人为污染等因素,分别分析阐述了风暴潮、相对海平面上升和赤潮这3种主要海洋灾害的形成原因和发展趋势,及其对天津市沿海地区社会、经济和生态环境方面施加的严重影响。  相似文献   

Laboratory study and predictive modeling for thaw subsidence in deep permafrost     

ZhaoHui Joey Yang  Gabriel T. Pierce 《寒旱区科学》2021,13(2):95-106

Oil wells on the North Slope of Alaska pass through deep deposits of permafrost. The heat transferred during their operation causes localized thawing, resulting in ground subsidence adjacent to the well casings. This subsidence has a damaging effect, causing the casings to compress, deform, and potentially fail. This paper presents the results of a laboratory study of the thaw consolidation strain of deep permafrost and its predictive modeling. Tests were performed to determine strains due to thaw and post-thaw loading, as well as soil index properties. Results, together with data from an earlier testing program, were used to produce empirical models for predicting strains and ground subsidence. Four distinct strain cases were analyzed with three models by multiple regression analyses, and the best-fitting model was selected for each case. Models were further compared in a ground subsidence prediction using a shared subsurface profile. Laboratory results indicate that strains due to thaw and post-thaw testing in deep core permafrost are insensitive to depth and are more strongly influenced by stress redistributions and the presence of ice lenses and inclusions. Modeling results show that the most statistically valid and useful models were those constructed using moisture content, porosity, and degree of saturation. The applicability of these models was validated by comparison with results from Finite Element modeling.  相似文献   

华北地区铅锌矿资源特征及成矿规律          下载免费PDF全文

付超  李俊建  党智财  张彤  彭翼  宋立军  侯占国  倪振平 《地质找矿论丛》2021,36(1):1-11

华北地区铅锌矿资源丰富、类型多样,是我国铅锌矿床的重要产区.本文在总结资源禀赋、矿床类型、时空特征、主要控矿因素、资源潜力等要素基础上,较全面分析了华北地区铅锌矿的主要特征和成矿规律.研究表明,从矿床成因角度,华北地区铅锌矿可划分为岩浆热液型、碳酸盐岩-细碎屑岩型、陆相火山岩型、矽卡岩型、斑岩型、碳酸盐型等6种类型,并...  相似文献   

辽中南城市群农业多功能演变特征与地域模式     

刘本城  房艳刚 《地理科学》2020,40(10):1720-1730

以辽中南城市群为例,构建农业多功能评价指标体系,采用时空差异诊断模型、回归分析、聚类分析等方法,对城市群农业地域多功能演变特征和地域模式进行实证研究。研究表明：① 2006—2016年辽中南城市群农业多种功能演变具有不同特征,农产品供给功能增强,增幅较大县域集中在康平、辽中和宽甸的“L型”连接线上;经济发展功能增强,增幅明显县域分布在本溪的市辖区;社会保障功能增强,增强明显县域包括大连、本溪的部分县域;生态服务功能减弱,减幅明显县域主要是金州、双台子、兴隆台、昌图等区县;休闲与文化功能增强,增幅较大县域集中在辽中南城市群南部沿海区县。② 农业多功能演变受到稳定性因素和驱动性因素共同影响,不同因素的作用方向与强度不同。③ 辽中南城市群农业多功能演变可划分为5种地域模式,应有针对性的采取差异化的发展策略。  相似文献   

基于地貌分区的陕西省区域生态风险时空演变   总被引：3，自引：0，他引：3  

刘迪  陈海  耿甜伟  张行  史琴琴 《地理科学进展》2020,39(2):243-254

论文采用“概率—损失”二维风险模型解构陕西省区域生态风险,基于地貌分区视角识别多源风险类型的同时以景观格局与生态系统服务价值为关联要素合成潜在生态损失,在此基础上分析了陕西省2000—2015年单一风险要素及区域生态风险的时空分异,并基于地貌分区视角结合重心模型探讨了生态风险的时空迁移。结果如下：① 2000、2015年陕西省多源危险度分别为0.3837、0.4558,上升18.79%,大致呈现南北高、中间低的空间格局,沿南北轴线呈现“W型”展布;潜在生态损失分别为0.5537、0.6270,上升13.24%,除高原南部与秦岭东部山区外,生态损失均呈现高值;区域生态风险分别为0.2429、0.2865,上升17.95%,空间上呈现“三高夹两低”的分布格局。② 从时序变化来看,秦巴山地保持较低风险且风险变化率较小;黄土高原与风沙过渡区变化率处于中等,后者面临较高风险;汉江盆地风险最高,该区域与关中平原分别为风险变化率的首位与次位。从生态风险重心变化趋势看,黄土高原与风沙过渡区重心均向西南移动,关中平原与秦岭山地重心东移趋势明显,汉江盆地与大巴山地重心跃向东南。  相似文献   

基于匹配滤波的多次波压制方法研究   总被引：13，自引：13，他引：0       下载免费PDF全文

李景叶  陈小宏  芮振华 《地球物理学进展》2007,22(1):200-206

常规滤波方法对浅海多次波压制不能取得理想效果.通过改变模型表面边界条件,求解波动方程实现多情景地震数值模拟.利用自由边界条件模拟时获得含海平面强反射多次波地震记录,而利用吸收边界条件时得到理想条件下无多次波地震记录.对比分析多次波对有效地震信号的影响得到海平面强反射多次波改变了有效地震信号的振幅、频率和相位.利用归一化方法计算得到压制多次波滤波器算子,并作用于含海平面强反射多次波地震记录.叠加地震剖面对比分析表明,归一化滤波器算子较好的压制了地震记录中的多次波,提高地震资料分辨率.最后,根据多次波产生条件,给出了利用实际区域简化地质模型的地震数值模拟结果计算归一化滤波器算子的方法,从而利用该方法压制实际地震数据中多次波.  相似文献   

鄂尔多斯盆地上三叠统延长组长7段深水重力流沉积类型   总被引：1，自引：0，他引：1  

张倚安  李士祥  田景春  周新平  杨田 《沉积学报》2021,39(2):297-309

以鄂尔多斯盆地上三叠统延长组长7段取芯段为主要研究对象,以详细的岩芯观察为基础,以Z43井为例,研究鄂尔多斯盆地延长组长7段深水重力流沉积类型及其特征.研究结果表明,研究区主要发育砂质碎屑流沉积、低密度浊流沉积及混合事件层三种沉积类型.砂质碎屑流沉积整体呈块状,岩性为中—细砂岩,内部可见多个接触面,为多套砂质碎屑流沉积...  相似文献   

中亚干旱区陆地水资源对气候变化的响应     

周启鸣  李剑锋  崔爱红  刘会增 《水文》2021,41(2):8-13,74

气候变化对中亚干旱区高山融雪、蒸散发以及径流等水循环过程产生影响,从而引起区域水资源在空间和时间上的重新分配.在归纳总结降水、土壤水、地表水、陆地水储量等不同水体类型在气候变化下改变情况的基础上,综述了中亚干旱区陆地水资源变化对气候变化响应的现状及进展.由于使用的数据和评估方法不同,水资源变化研究结果具有一致性及不确定...  相似文献   

基于S波段双偏振雷达资料的降水粒子类型识别算法及应用          下载免费PDF全文

宋文婷  李昀英  黄浩  朱科锋 《大气科学学报》2021,44(2):209-218

基于质量控制的S波段双偏振雷达格点化观测数据,利用模糊逻辑算法,结合降雨粒子散射和空间取向等特征建立了降水粒子类型识别算法,用于分析降水过程中降水粒子的空间分布情况及粒子类型的演变过程.该算法可以将降水粒子分为液态、冰态、混合态等不同种类,有助于发现影响降水多寡的云微物理关键结构.首先根据不同降水粒子的雷达回波特性得到...  相似文献