用Gumbel极值分布推算气候极值的方法

介绍了用Gumbel极值分布理论推算气候极值的矩法、Thomas曲线公式和最小二乘法。并计算多年一遇的年最高气温、年最大均风速、年最大日降雨量和年最大波高。指出,变率小的要素极值再现期短;变率大的要素极值再现期长;Thomas曲线公式的计算结果较其它两种方法接近历史实况,且计算简便。     

Appraisal of storm beach buffer width for cyclonic waves

The loss of beach sand from berm and dune due to high waves and surge is a universal phenomenon associated with sporadic storm activities. To protect the development in a coastal hazard zone, hard structures or coastal setback have been established in many countries around the world. In this paper, the requirement of a storm beach buffer, being a lesser extent landward comparing with the coastal setback to ensure the safety of infrastructures, is numerically assessed using the SBEACH model for three categories of wave conditions in terms of storm return period, median sand grain size, berm width, and design water level. Two of the key outputs from the numerical calculations, berm retreat and bar formation offshore, are then analysed, as well as beach profile change. After having performed a series of numerical studies on selected large wave tank (LWT) test results with monochromatic waves using SBEACH, we may conclude that: (1) Berm erosion increases and submerged bar develops further offshore as the storm return period increases for beach with a specific sand grain size, or as the sand grain reduces on a beach under the action of identical wave condition; (2) Higher storm waves yield a large bar to form quicker and subsequently cause wave breaking on the bar crest, which can reduce the wave energy and limit the extent of the eroding berm; (3) A larger buffer width is required for a beach comprising small sand grain, in order to effectively absorb storm wave energy; and (4) Empirical relationships can be tentatively proposed to estimate the storm beach buffer width, from the input of wave conditions and sediment grain size. These results would benefit a beach nourishment project for shore protection or design of a recreational beach.     

Geoarchaeological evidence on a Late Bronze Age earthquake,Ohrid Basin (North Macedonia)

Geoarchaeological investigations on the northeastern shore of Lake Ohrid revealed 3.5 m thick deepwater lacustrine sediments overlying terrestrial vegetation macrofossils, worked wood and abundant potsherds dated to the Late Bronze Age (LBA). Distinct contact of deepwater sediment with the sub-aerial weathered limestone bedrock point to a sudden increase in lake level. According to radiocarbon data, catastrophic flooding occurred shortly after 1214 yr bc. Because the area is located in a highly active seismic zone, we propose that this event was caused by tectonically induced, metre-scale coseismic subsidence related to faults bordering the Ohrid alluvial plain. Moreover, this event coincides well with a dramatic switch in the habitation and settlement strategy in the region. More important, however, is the finding that the age of the proposed massive tectonic event and change in habitation lies within the interval of the proposed ‘earthquake storm’ in the eastern Mediterranean dated to 1225–1175 bc. As the Ohrid-Korça zone belongs to the same tectonic province, a relationship between the abovementioned earthquakes and the proposed event can be expected. This research therefore might provide the first direct evidence of a large-scale earthquake event linkable to the LBA collapse of Europe's first urban civilisation in the Aegean.     

塔里木盆地沉积剥蚀过程与油气关系

塔里木盆地典型井的周期分析表明,塔里木盆地在其地质历史时期100Ma左右的周期是很明显的,自寒武纪以来共经历了4个完整的周期,每一完整周期都由正相位和负相位两个半周期所组成。而第三纪为第5个周期的正相位阶段。该周期控制了盆地内的沉积与剥蚀的过程及成藏旋回。对沉积与剥蚀过程的控制作用表现在周期波正相位和负相位分别对应于沉积期和剥蚀期,这在地质年代序列中表现为沉积与间断的互为消长的演化进程。对食油气系统的控制作用表现在:第1个周期波构成以早古生代地层为主体的含油气系统,第2个周期波至第4个周期波构成以晚古生代至中生代地层为主体的含油气系统,第5个周期的正相位阶段构成以第三纪地层为主体的含油气系统。     

A study of design spectra based on attenuation relationship of ground motion

In recent years, more and more studies are focused on the performance in seismic design instead of the strength of structures. People have realized that the structure deformation (displacement) can describe the damage more properly and directly than the strength (force). The displacement design spectra need to be constructed within more wide range of the period and the damping for the displacement-based seismic design.     

莱芜市汛期地质灾害防治方案初探

莱芜市是一个矿产资源开采历史比较悠久的城市,也是一个地质灾害多发的地区。莱芜市国土资源局通过加强组织领导,组织专题宣传活动,修复治理损毁山体问题,加大日常监管措施,推进生产矿山的恢复治理等措施,取得良好的治理效果,矿山地质环境恢复治理率达66％,有效保护了当地的地质环境。     

Cenozoic uplift of Variscan Massifs in the Alpine foreland: Timing and controlling mechanisms

The European Cenozoic Rift System (ECRIS) and associated fault systems transect all Variscan Massifs in the foreland of the Alps. ECRIS was activated during the Eocene in the foreland of the Pyrenees and Alps in response to the build-up of collision-related intraplate stresses. During Oligocene and Neogene times ECRIS evolved by passive rifting under changing stress fields, reflecting end Oligocene consolidation of the Pyrenees and increasing coupling of the Alpine Orogen with its foreland. ECRIS is presently still active, as evidenced by its seismicity and geodetic data.Uplift of the Massif Central and the Rhenish Massif, commencing at the Oligocene–Miocene transition, is mainly attributed to plume-related thermal thinning of the mantle–lithosphere. Mid-Burdigalian uplift of the SW–NE-striking Vosges–Black Forest Arch, that has the geometry of a doubly plunging anticline breached by the Upper Rhine Graben, involved folding of the lithosphere. Late Burdigalian broad uplift of the northern parts of the Bohemian Massif reflects lithospheric buckling whereas late Miocene–Pliocene uplift of its marginal blocks involved transpressional reactivation of pre-existing crustal discontinuities. Crustal extension across ECRIS, amounting to no more than 7 km, was compensated by a finite clockwise rotation of the Paris Basin block, up warping of the Weald–Artois axis and reactivation of the Armorican shear zones. Intermittent, though progressive uplift of the Armorican Massif, commencing in the Miocene, is attributed to transpressional deformation of the lithosphere.Under the present-day NW-directed compressional stress field, that came into evidence during the early Miocene and further intensified during the Pliocene, the Armorican Massif, the Massif Central, the western parts of the Rhenish Massif and the northern parts of the Bohemian Massif continue to rise at rates of up to 1.75 mm/y whilst the Vosges–Black Forest arch is relatively stable.Uplift of the Variscan Massifs and development of ECRIS exerted strong controls on the Neogene evolution of drainage systems in the Alpine foreland.     

Probability-consistent spectrum and code spectrum

IntroductionInChina,thecombinationofseismicdesigncodewithzoningmapofseismicintensityorgroundmotionparametersisusuallyadoptedtodeterminetheseismicfortificationcriterionforthegeneralindustryandcivilbuildings.Thepresentproceduresareasfollows.Accordingtothepro-jectlocation,thedesignbasicaccelerationofgroundmotionandthedesigncharacteristicperiodofresponsespectrumareobtainedfromthezoningmapofseismicgroundmotionparameters(GeneralAdministrationofQualitySupervision,InspectionandQuarantineofthePeople…     

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