Recurrence characteristics of late-quaternary strong earthquakes on the major active faults along the northern border of Ordos block

Through study on trenches, analysis of recurrence characteristics and recurrence interval cluster/gap of strong earthquakes along the major active faults on the northern border of Ordos block, we found 62 paleoearthquakes that occurred in the late Quaternary, including 33 earthquakes occurring in the Holocene. The recurrence characteristics of the paleoearthquakes are different at three levels, segments, faults, and fault zones. The strong seismic sequence on the independent segments is mostly characterized by long- and short-interval recurrences, while that on the faults and in fault zone is characterized clearly by random and cluster recurrences. Results of the moving window test indicate that the probabilities of "temporal cluster or gap", caused by random coincidence as opposed to intersegment contagion, are 64% and 70% for the Serteng piedmont fault and for the south-border fault of Wula Mountains, respectively, no clear interaction among the segments of each fault; while the probability is 26.8% for the whole fault zone, suggesting a clear interaction among the faults of this fault zone. These recurrence characteristics may imply an effect of the entire block motion on the recurrence of strong earthquakes. Moreover, the elapsed time for the Wujumeng Pass-Dongfeng Village segment of Serteng piedmont fault and the Tuzuo Banner-Wusutu and the Hohhot segments of Daqingshan piedmont fault has exceeded the average recurrence interval, hence these three segments may be the possible places for future strong earthquakes.     

古洪水流量的误差计算

古洪水研究已在大型工程和长江三峡，黄河小浪底等的设计洪水中得到动用取得了令人虚心成功，但古洪水流量的推求与实测量的计算往往有大的差别，根据随机误差的传播给出了一般情况下的古洪不流量推误差计算公式，以小流底２３６０ａＢＰ古洪水注同误差的计算为例，对最终计算出的古洪水流量成果给出了一个误差范围。     

晚更新世晚期以来的长江上游古洪水记录

长江上游三峡河段主要的古洪水记录有:1)三峡深槽的蚀积变化;2)长江阶地粗粒沉积;3)长江的泛滥沉积;4)长江的古洪水平流沉积。不同时间跨度不同类型古洪水记录的精度有较大的差别。古洪水记录显示,晚更新世晚期的40～30kaB.P.,长江上游大洪水比30kaB.P.以来的长江上游大洪水大得多;全新世以来,以3983aB.P.前后的大洪水为相对最大;公元1870年大洪水为3000aB.P.以来最大洪水;近百年来的实测洪水以公元1981年洪水为最大。     

Meteorological Office, Pune-411 005

Natural disasters like floods, tornadoes, tropicalcyclones, heat and cold wavewreak havoc and cause tremendous loss ofproperty all over the world. Most ofthe natural disasters are either dueto weather or are triggered due toweather related processes.Extreme weather events claimed thousands oflives and caused damage on vastscale. Recent super cyclone which affectedOrissa in 1999, Bangladesh cyclone of1970 and Hurricane Andrew in 1992 areexamples of some of the more damagingtropical cyclones which affected developingas well as the developed world. Heatand cold waves are also extreme events,which cause enormous losses in terms oflives lost and human discomfort and ailmentsarising out of them. The heat waveof 1995 and 1998 are still fresh in the mindof the Indian public. The estimated lossof human lives due to heat wave in 1998 was morethan 15,000. Economic losses asa result of these disasters and in particular inassociation with tropical cyclones haveincreased enormously over the last three decades.During 1961–1991, total loss oflives from drought alone was 1,333,728 overthe whole world. In terms of economiclosses, there is 8–10 fold increase from thebase figure of 1960. The socio-economicimpact of natural disaster is complex dependingupon the vulnerability of the placeand mitigation strategies that are put in place.Meteorology plays a crucial role in forewarningpeople about the severe/extremeweather systems and a constant endeavour by themeteorological services worldover has gone a long way towards minimizing thelosses caused by natural disasters.The paper summarises the natural disasterstatistics over south Asia and the possibleprediction strategies for combating theirsocio-economic impacts.     

孟湾槽在百色市异常降雪天气中的作用

通过对1983年12月28日、2002年12月26日百色市两次异常降雪天气过程的对比分析,发现冬季孟加拉湾槽的发展东移在其中起到了关键性的作用。由于孟加拉湾槽前暖湿气流强盛,这种强盛的西南暖湿气流在低空冷空气堆(冷锋)上发生强烈的系统性上升运动,从而导致百色市及其邻近地区出现异常的雨雪天气。     

Late Quaternary systematic stream offsets caused by repeated large seismic events along the Kunlun fault, northern Tibet

The Kunlun fault is one of the largest strike-slip faults in northern Tibet, China. In this paper, we focus upon the Kusai Lake–Kunlun Pass segment of the fault to understand the geomorphic development of offset streams caused by repeated large seismic events, based on tectono-geomorphic analysis of high-resolution satellite remote sensing images combined with field studies. The results indicate that systematic left-lateral stream offsets appear at various scales across the fault zone: Lateral offsets of small gullies caused by the 2001 M_w 7.8 Kunlun earthquake vary typically from 3 m to 6 m, meanwhile streams with cumulative offsets of 10 m, 25–30 m, 50–70 m, 250–300 m and 750–1400 m have resulted from repeated large seismic events during the late Quaternary. An average slip rate of 10 ± 1 mm/year has been estimated from the lateral stream offsets and ¹⁴C ages of alluvial fan surfaces incised by the streams. A three-dimensional model showing tectono-geomorphic features along a left-lateral strike-slip fault is also presented. The Kusai Lake–Kunlun Pass segment provides an opportunity to understand the relationship between geomorphic features produced by individual large seismic events and long-term geomorphic development caused by repeated large seismic events along a major strike-slip fault.     

河南嵩山地区新元古界何家窑组微亮晶脉特征、成因及地质意义探讨

在河南嵩山地区青白口系何家窑组中可识别出一个碳酸盐岩微亮晶脉集中的层位，笔者等结合微亮晶脉自身的特征、成分和伴生的地震引起的其他变形特征，以及通过显微镜和核磁共聚焦显微镜下的微相研究，认为嵩山地区板状微亮晶脉与华北块体东缘胶辽徐淮地区的泥晶脉特征一致，是由地震液化形成的产物，该层位代表了一个地震活跃期。同处华北块体南缘的豫西鲁山和陕西南部相对应的青白口系层位（洛峪口组和巡检司组）也发现了同期的地震记录。笔者认为嵩山地区微亮晶脉的出现应与华北块体南缘构造事件相关联。     

A new magnitude category disaggregation approach for temporal high‐resolution rainfall intensities

Simulation of quick runoff components such as surface runoff and associated soil erosion requires temporal high‐resolution rainfall intensities. However, these data are often not available because such measurements are costly and time consuming. Current rainfall disaggregation methods have shortcomings, especially in generating the distribution of storm events. The objectives of this study were to improve point rainfall disaggregation using a new magnitude category rainfall disaggregation approach. The procedure is introduced using a coupled disaggregation approach (Hyetos and cascade) for multisite rainfall disaggregation. The new procedure was tested with ten long‐term precipitation data sets of central Germany using summer and winter precipitation to determine seasonal variability. Results showed that dividing the rainfall amount into four daily rainfall magnitude categories (1–10, 11–25, 26–50, >50 mm) improves the simulation of high rainfall intensity (convective rainfall). The Hyetos model category approach (Hyetos_Cat) with seasonal variation performs representative to observed hourly rainfall compared with without categories on each month. The mean absolute percentage accuracy of standard deviation for hourly rainfall is 89.7% in winter and 95.6% in summer. The proposed magnitude category method applied with the coupled Hyetos_Cat–cascade approach reproduces successfully the statistical behaviour of local 10‐min rainfall intensities in terms of intermittency as well as variability. The root mean square error performance statistics for disaggregated 10‐min rainfall depth ranges from 0.20 to 2.38 mm for summer and from 0.12 to 2.82 mm for the winter season in all categories. The coupled stochastic approach preserves the statistical self‐similarity and intermittency at each magnitude category with a relatively low computational burden. Copyright © 2014 John Wiley & Sons, Ltd.