高分辨湖泊沉积和孢粉记录对气候、水文变化的响应

通过对长江中游网湖钻孔高精度分层样品(1.5年/样品)的沉积学和孢粉学研究,试图揭示过去百年网湖在由开放到封闭体系变化中,沉积孢粉与气候、水文动力变化的过程及其相互关系.相关分析和低频滤波分析,反映出沉积物和孢粉的变化对流域降水和长江流量的敏感响应.在过去130年中的多雨洪水年份,湖泊受长江倒灌影响,沉积物以黏土细颗粒...     

历史极端雨涝事件研究——1823年我国东部大范围雨涝

1823年(清道光三年)我国发生大范围、多流域的严重雨涝,这是在小冰期寒冷气候背景下的重大气象灾害和极端气候事件.文章依据历史文献记载复原了1823年的气候实况并绘图显示,指出该年我国华北夏季雨期长、多大雨,北京6～8月雨日53天、降水量663mm超过现代(1971～2000年)平均值5成;长江中下游全年多雨,梅雨期长...     

三眼峪特大泥石流堆积特征

通过野外勘查与试验,认为三眼峪泥石流沟是一个高频泥石流沟,历史上发生多次重大泥石流灾害事件,多期泥石流堆积物在沟道及沟口上下超覆叠置。结合泥石流发生前后遥感影像对比,采用ArcGIS平台进行分析,“8．8”特大泥石流一次最大冲出固体物质总量达152．18×10^4m^3,所到之处房毁江堵,并形成长约1．9km的狭长堆积,堆积量110．58×10^4m^3,最大堆积厚度达10．8m。因泥石流堆积特征是泥石流发生、发展、活动过程的客观记录,分析了三眼峪早期和“8．8”泥石流在不同部位的堆积特征和破坏程度,为泥石流综合整治和灾后重建规划提供参考。     

1819年黄河中游极端降水:史实、特征及气候背景

据清官档案与方志记载,复原了1819年(清嘉庆二十四年)黄河中、下游大范围房屋倒塌、民田冲没、人口伤亡、黄河多处决溢等雨涝灾情图景及时空分异特征,这是在明清小冰期大气候背景下的极端气候事件和重大气象灾害.研究指出,该年黄河中游夏秋季雨期长(连阴雨)、且多大到暴雨,二级流域(汾河、渭河)6-9月份降水县区雨日高达40日以...     

中国木叶鲽属鱼类一新纪录种

2008年8月,在浙江舟山附近海域(东海)采集到4尾木叶鲽属鱼类,经鉴定为中国鱼类新纪录种——长木叶鲽,其主要特征为:体棕褐色,有眼侧和无眼侧颞上枝前端有小分枝,鳞片小但不狭长,背鳍鳍条数72~74(73.3);臀鳍鳍条数56~59(57.5);有眼侧胸鳍鳍条数8~10(8.8),无眼侧胸鳍鳍条数为8;有眼侧与无眼侧腹鳍鳍条数均为6;尾鳍鳍条数19~20(19.5),脊椎骨数为36;鳃耙数为3+7。基于线粒体COI基因片段得到的长木叶鲽与角木叶鲽的K2P遗传距离为9.4%,2种间遗传分化达到了种间水平。     

Tectonic Taphrogenesis and Paleoseismic Records from the Yishu Fault Zone in the Initial Stage of the Caledonian Movement

The Yishu fault zone (mid-segment of the Tanlu fault zone) was formed in the Presinian. Periodic tectonic activities and strong seismic events have occurred along the fault zone. During the initial stage of the Caledonian Movement, with the proceeding of the marine transgression from the Yishu paleo-channel to the western Shandong, uneven thick sediments, composed mainly of sand, mud and carbonates of littoral, lagoon, and neritic facies, were deposited in the Yishu fault zone and western Shandong, and constructed the bottom part of the Lower Cambrian consisting of the Liguan and Zhushadong formations. Through field observations and the lab-examinations, various paleoseismic records have been discovered in the Liguan Formation and the Zhushadong Formations of the Yishu fault zone and its vicinity, including some layers with syn-sedimentary deformation structures that were triggered by strong earthquakes (i.e. seismite, seismo-olistostrome, and seismo-turbidite). Paleoseismic records developed in the Zhushadong Formation are mainly seismites with soft-sediment deformation structures, such as liquefied diapir, small liquefied-carbonate lime-mud volcano, liquefied vein, liquefied breccia, convolute deformation (seismic fold), graded fault, soft siliceous vein, and deformation stromatolite, as well as seismites with brittle deformation structures of semiconsolidated sediments. Paleoseismic records preserved in the Liguan Formation are not only seismo-olistostrome with a slump fold, load structure, and ball-and-pillows, but also seismo-turbidite with convolution bedding, graded bedding and wavy-bedding. However, in the western Shandong area, the closer to the Yishu fault zone, the greater the thickness of the Liguan Formation and the Zhushadong Formation, the greater the number and type of layers with paleoseismic records, and the higher the earthquake intensity reflected by associations of seismic records. This evidence indicates that tectonic taphrogenesis accompanied by strong earthquake events occurred in the Yishu fault zone during the initial stage of the Caledonian Movement, which embodied the break-up of the Sino-Korean Plate along the Paleo-Tanlu fault zone at that time.     

Evidence for repeated re‐activation of old landslides under forest

Local reactivations of landslides in forests are rarely reported in landslide catalogues. The occurrence of hillslope sections with fresh morphological landslide features in forested old, deep‐seated landslides, however, suggests that landslide reactivations are not restricted to residential areas. In this study, a dendrogeomorphological analysis of beech stands was used to investigate the periods of reactivation of a deep‐seated rotational slide in the Koppenberg forest (Flemish Ardennes, Belgium). The relation to rainfall and the correspondence to landslide reactivations reported in a nearby built‐up area were also analysed. A dendrometrical study preceding the dendrochronological analysis proved that, compared with the nearby reference site, trees on the Koppenberg forest landslide site were significantly more inclined and showed more knees, indicating that the landslide site has not stabilized yet. As the sampled trees are younger than the landslide, dendrochronology did not allow determination of the year in which the landslide was initiated, but analysis of two different tree ring width parameters (i.e. ring eccentricity and growth change) calculated for trees sampled on the Koppenberg landslide and the reference site proved to be of great help in determining the temporal sequence of landslide reactivation. During the past 80 years, several periods indicative of local reactivations (i.e. 1943–1945, 1949–1952, 1967–1970, 1972–1977, 1979–1981, 1988–1997) were found within the investigated landslide, but delineation of the spatial extent of the reactivations during these indicative periods was not straightforward. These periods generally correspond to years with above‐average rainfall. Finally, the fact that at least 34% of the years indicative of reactivation of the Koppenberg forest landslide correspond to a year in which a landslide reactivation was reported in the Flemish Ardennes suggests that in built‐up areas, apart from anthropogenic interventions, natural triggering factors remain very important. Copyright © 2009 John Wiley & Sons, Ltd.     

Original technologies for proven performances for the new LCPC earthquake simulator

The European Quaker project has been a powerful opportunity to accelerate the development of the ability to carry out earthquake simulations at reduced scale in the centrifuge in LCPC—France. This paper summarizes the main original technologies of this simulator. The quality of the checked performances is demonstrated in terms of ability to perform since earthquakes as well as to simulate scaled records of real earthquakes. The consistancy of the results is presented in the time and in the frequency domains.     

1208-1369年陕甘宁交界地区干湿变化

More than 240 items of historical records containing climatic information were retrieved from official historical books, local chronicles, annals and regional meteorological disaster yearbooks. By using moisture index and flood/drought (F/D) index obtained from the above information, the historical climate change, namely wet-dry conditions in borderland of Shaanxi Province, Gansu Province and Ningxia Hui Autonomous Region (BSGN, mainly included Ningxialu, Hezhoulu, Gongchanglu, Fengyuanlu and Yan’anlu in the Yuan Dynasty) was studied. The results showed that the climate of the region was generally dry and the ratio between drought and flood disasters was 85/38 during the period of 1208–1369. According to the frequencies of drought-flood disasters, the whole period could be divided into three phases. (1) 1208–1240: drought dominated the phase with occasional flood disasters. (2) 1240–1320: long-time drought disasters and extreme drought events happened frequently. (3) 1320–1369: drought disasters were less severe when flood and drought disasters happened alternately. Besides, the reconstructed wet-dry change curve revealed obvious transition and periodicity in the Mongol-Yuan Period. The transitions occurred in 1230 and 1325. The wet-dry change revealed 10- and 23-year quasi-periods which were consistent with solar cycles, indicating that solar activity had affected the wet-dry conditions of the study region in the Mongol-Yuan Period. The reconstructed results were consistent with two other study results reconstructed from natural evidences, and were similar to another study results from historical documents. All the above results showed that the climate in BSGN was characterized by long-time dry condition with frequent severe drought disasters during 1258 to 1308. Thus, these aspects of climatic changes might have profound impacts on local vegetation and socio-economic system.     

历史将永远铭记他们——记在叠溪大地震的考察、研究和救灾工作中作出贡献的几位前辈

考证并记叙了在1933年叠溪地震的考察、研究和救灾工作中作出过重要贡献的若干前辈的事迹,包括常隆庆、李善邦、周郁如、徐近之、庄学本、张雪岩等先生和四川大学的师生们。他们是中国地震科学和防震减灾事业的先行者,永远值得我们怀念。