“Terrae motus factus est”: earthquakes in Switzerland before A.D. 1000. A critical approach     

Monika Gisler  Donat Fäh  Virgilio Masciadri 《Natural Hazards》2007,43(1):63-79

We focus on Swiss earthquakes in antiquity and the early medieval period before A.D. 1000. We have information on less than half a dozen earthquakes within this era, since written records for the first half of the first millennium A.D. are minimal, and there is little hope of finding more written evidence for earthquakes. Furthermore, interpreting the documents at hand is somewhat complex. For the 6th century Gregory of Tours in Historia Francorum gives hints of a rockslide near the castle Tauredunum (Le Grammont) in the Swiss canton Valais, an event that has been considered in the literature as caused by an earthquake. The Carolingian period (ca. 750–950) included the rise of some very important cultural centers in various parts of today’s Switzerland. For instance, the ecclesiastical culture in St. Gallen generated a remarkable number of written records, which survived for our use in a unique manner. From the 9th and 10th centuries, we have evidence for earthquakes in the years 849, 867, 902, and 944. However, information on them remains so scarce that their location and intensity are generally difficult to assess. Nevertheless, the finding of a new document - a memoir written by the abbot of Reichenau - offers some insight into the A.D. 849 event and its reportedly aftershocks.

Monika GislerEmail:

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球面圆弧数字地形剖面提取方法研究     

张玲  梁诗明 《震灾防御技术》2022,17(1):79-83

带状地形剖面是以高程为纵向参考,以距剖面起始端点的距离为横向参考进行制图表达。由于其可真实地反映地表形态,是新构造和活动构造地貌研究中的基本参考和研究对象。随着数字化基础地理信息成果的普及,很多GIS软件可实现地形剖面的自动化提取。但以往方法的位置信息均是建立在剖面投影平面的基础上,当研究区域范围过大,会引入非构造变形,为消除该影响,提出基于球面坐标系统的带状地形剖面图制作方法。该方法不仅适用于小型地质构造,也适用于喜马拉雅弧形造山带等大型地质构造,可提取出更接近真实地形的地形剖面。  相似文献   

基于我国实际工程场地的不同基本周期计算方法差异性研究          下载免费PDF全文

李明睿  李瑞山  袁晓铭  陈卓识 《世界地震工程》2022,38(4):036-43

场地基本周期是表征场地动力特性最基本的指标,也是评价场地条件的重要依据。本文介绍了计算场地基本周期的四种方法——子层周期求和法（规范法）、子层周期贡献系数法、简化Rayleigh法以及逐层单自由度法。收集并筛选了国内605组钻孔深度达到工程基岩的剪切波速剖面资料,其中:Ⅰ类场地10个;Ⅱ类场地300个;Ⅲ类场地249个;Ⅳ类场地46个。以传递函数法结果为标准,对上述四种方法的计算结果进行对比检验,就不同方法的偏差进行了深入分析,给出了其统计结果,并剖析了各方法应用于实际工程场地的适宜性。主要结论:（1）我国规范所采用的子层周期求和法虽然在工程中方便使用,但计算结果普遍存在显著偏差,其偏差的平均值大于20%,最大偏差甚至接近50%。（2）简化Rayleigh法和逐层单自由度法相较于规范法计算精度均有大幅提高,二者偏差在5%以内的工况数占比分别达到80%和70%以上。（3）子层周期贡献系数法采用了加权累加的计算方式,继承了规范法便于操作的优点,并且计算精度为本文所选四种方法中最高,其最大偏差不超过10%,偏差在5%以内的工况数占比达到85%,建议在实际工程中推广应用。  相似文献   

藏南嘉黎断裂古乡—通麦段多期活动特征及其构造意义     

赵远方  公王斌  江万  陈龙耀  仇度伟 《现代地质》2021,35(1):220-233

嘉黎断裂是青藏高原南部呈北西西—南东东向喀喇昆仑—嘉黎断裂系的重要组成部分,被认为代表了北拉萨地块和中拉萨地块之间的构造界线。关于嘉黎断裂的构造性质和演化过程等仍存在争议,其不同期次构造过程仍需要进一步研究。在详细的区域地质填图基础上,以嘉黎断裂古乡—通麦段为研究对象,重点调查了该断裂带不同期次变形的几何学与运动学特征,基于新获得的不同方位断层面与擦痕特征等资料,恢复和计算该区的不同期次应力场及方向,并据此解析该区的多期构造叠加关系,探讨嘉黎断裂在不同应力场下的多期活动特征以及相关的区域构造演化过程和大地构造背景,在此基础上讨论了嘉黎断裂对拟建铁路工程的影响。研究结果显示,嘉黎断裂晚新生代以来仍有活动迹象,并具有多期构造叠加特征,从早到晚依次为左旋走滑(D₁)、正倾滑(D₂)和右旋走滑(D₃)。嘉黎断裂作为东喜马拉雅构造结地区重要的变形调节构造,其多期活动性质反映了地块间的相对运动特征及区域应力场的转换过程,这对认识青藏高原南缘的新生代构造演化过程具有重要意义。  相似文献   

复合点坝侧积周期的成因分析:以密西西比河下游段为例^*          下载免费PDF全文

范洪军  王夏斌  胡光义  范廷恩  何明薇  陈飞 《古地理学报》2021,23(2):421-434

复合点坝侧积体定量成因分析是河流沉积学研究的难点之一。通过选取密西西比河下游段激光雷达数据,剖析复合点坝侧积体的内部特征,统计侧积体高程数据,发现其符合周期变化的特点。对高程数据进行傅里叶变换计算,得到复合点坝侧积周期,将侧积周期与河道规模进行拟合,两者符合线性关系,拟合度高。深入分析后,认为侧积周期受河流的季节性洪泛周期控制。研究结论为侧积体定量成因分析提供了理论依据。  相似文献   

油源断裂油气成藏期优势通道输导能力综合评判方法及其应用     

袁红旗  魏鸣禄  于英华 《吉林大学学报(地球科学版)》2021,51(3):694-703

本文通过油气成藏期油源断裂不同部位古活动速率相对大小分布,确定其油气输导的优势通道。并基于优势输导通道的断裂古活动速率、古倾角、目的层古埋深和源岩古剩余地层压力等指标,建立了一套油源断裂在油气成藏期优势通道输导能力的综合评判方法。以渤海湾盆地冀中坳陷廊固凹陷为靶区,对大柳泉区块旧州油源断裂带在成藏期沙三中下亚段内的优势通道进行了厘定和油气输导能力综合评判。评判结果表明：旧州油源断裂6条分支断裂油气成藏期——沙二段沉积时期发育了10个优势通道,其油气输导能力以F₁和F₂分支断裂的6个优势通道输导油气能力相对较强,有利于油气运移,F₃、F₄、F₅和F₆分支断裂发育4个优势通道,其输导油气能力相对较弱,不利于油气运移。此评判结果与目前旧州断裂带附近沙三中下亚段内的油气分布现状相吻合,表明用此方法进行油源断裂成藏期优势通道的输导能力综合评判是可行性的。  相似文献   

The Zhaxikang Vein‐type Pb‐Zn‐Ag‐Sb Deposit in Himalayan Orogen,Tibet: Product by Overprinting and Remobilization Processes during Post‐collisional Period     

LIANG Wei  HOU Zengqian  ZHENG Yuanchuan  YANG Zhusen  LI Zhenqing 《《地质学报》英文版》2018,92(2):682-705

The Zhaxikang Pb-Zn-Ag-Sb deposit, the largest polymetallic deposit known in the Himalayan Orogen of southern Tibet, is characterized by vein-type mineralization that hosts multiple mineral assemblages and complicated metal associations. The deposit consists of at least six steeply dipping veintype orebodies that are hosted by Early Jurassic black carbonaceous slates and are controlled by a Cenozoic N–S-striking normal fault system. This deposit records multiple stages of mineralization that include an early period(A) of massive coarse-grained galena–sphalerite deposition and a later period(B) of Sb-bearing vein-type mineralization. Period A is only associated with galena–sphalerite mineralization, whereas period B can be subdivided into ferrous rhodochrosite–sphalerite–pyrite, quartz–sulfosalt–sphalerite, calcite–pyrite, quartz–stibnite, and quartz-only stages of mineralization. The formation of brecciated galena and sphalerite ores during period A implies reworking of pre-existing Pb–Zn sulfides by Cenozoic tectonic deformation, whereas period B mineralization records extensive openspace filling during ore formation. Fluid inclusion microthermometric data indicate that both periods A and B were associated with low–medium temperature(187–267°C) and low salinity(4.00–10.18% wt. Na Cl equivalent) ore-forming fluids, although variations in the physical–chemical nature of the period B fluids suggest that this phase of mineralization was characterized by variable water/rock ratios. Microprobe analyses indicate that Fe concentrations in sphalerite decrease from period A to period B, and can be divided into three groups with Fe S concentrations of 8.999–9.577, 7.125–9.109, 5.438–1.460 mol.%. The concentrations of Zn, Sb, Pb, and Ag within orebodies in the study area are normally distributed in both lateral and vertical directions, and Pb, Sb, and/or Ag concentrations are positive correlation within the central part of these orebodies, but negatively correlate in the margins. Sulfide S isotope compositions are highly variable(4‰–13‰), varying from 4‰ to 11‰ in period A and 10‰ to 13‰ in period B. The Pb isotope within these samples is highly radiogenic and defines linear trends in 206 Pb/204 Pb vs. 207 Pb/204 Pb and 206 Pb/204 Pb vs. 208 Pb/204 Pb diagrams, respectively. The S and Pb isotopic characteristics indicate that the period B orebodies formed by mixing of Pb–Zn sulfides and regional Sbbearing fluids. These features are indicative of overprinting and remobilization of pre-existing Pb–Zn sulfides by Sb-bearing ore-forming fluids during a post-collisional period of the Himalayan Orogeny. The presence of similar ore types in the north Rhenish Massif that formed after the Variscan Orogeny suggests that Zhaxikang-style mineralization may be present in other orogenic belts, suggesting that this deposit may guide Pb–Zn exploration in these areas.  相似文献   

辽北地区新元古代原殷屯组岩石地层单位的重新划分及其地质意义     

卢崇海  田德欣  李彪  邵九龙  刘振伟  赵娇  卢思桥 《世界地质》2018,37(4):1085-1091

本次研究把20世纪八十年代初期完成的辽宁1∶5万大甸子、下肥地和上年马洲幅区调报告中所建立的震旦系殷屯组3个岩性段,即底部砾岩段、中部砂岩段和上部板岩、页岩段,分别厘定为新元古界北方系(南华系)殷屯组、陈千户组和汎河组。并确认出殷屯组为辽宁北方系(南华系)第一次陆相冰碛作用的产物;陈千户组为陆相间冰期沉积的产物;汎河组为辽宁第二次陆相冰湖相堆积的产物。上述组级岩石地层单位的厘定,首次在辽宁北部地区划分出2次冰水堆积物。  相似文献   

西昆仑北缘沙拉吾如克铜铅矿地质特征及矿床成因浅析     

黄建国 《地质与勘探》2018,54(1):1-8

西昆仑北缘沙拉吾如克铜铅矿是区域内较为典型的矿床类型之一,矿体主要赋存于加里东期阿勒玛勒克杂岩体中,受沙拉吾如克断裂的控制。矿石矿物主要有黄铜矿、方铅矿、黄铁矿等,矿石铜铅品位相对较贫,一般Cu含量为0.50%~1.33%(平均0.7%),Pb为0.60%~5.99%(平均0.9%)。铜铅矿石的稀土总量(ΣREE)为83.5×10~(-6)~122×10~(-6),相对围岩(ΣREE为257×10~(-6)~342×10~(-6))来说,明显偏低。铜铅矿石的δEu为0.90~1.04,δCe为0.95~0.96,表现为铕和铈的无异常。含矿岩系稀土元素含量及配分模式显示出成矿元素直接来源于阿勒玛勒克杂岩体,特别是来自晚序次的似斑状石英二长岩或二长花岗岩(均为埃达克岩),矿床类型属于斑岩型矿床,为区域上加里东期成矿事件的产物,与大同一带加里东期铜钼矿的形成具有一致的大陆动力地质学过程,即原特提斯洋(西昆仑北洋)向南俯冲消减,进而引起花岗质岩浆活动并成矿。  相似文献   

黑龙江省气温演变及未来趋势分析   总被引：1，自引：0，他引：1  

高玉中  王承伟  王冀  胡文东 《冰川冻土》2018,40(2):270-278

利用1961-2015年的年平均及月平均气象资料,对黑龙江省全年、暖季与冷季平均气温进行分析,发现冷期和暖期持续时间相近,周期内的冷期和暖期平均气温相差较大。全年和冷季气温冷、暖期转换年份分别为1964年（暖转冷）、1988年（冷转暖）、2009年（暖转冷）;暖季气温转换年份分别为1969年（暖转冷）、1996年（冷转暖）、2015年前后（暖转冷）。利用模式方法和统计方法分别对2016-2030年黑龙江省气温变化趋势进行探讨,发现未来暖季和冷季气温上升幅度均变缓或者停滞,可能进入相对冷期。  相似文献