Constraining the characters of the upper mantle discontinuities beneath the NE margin of the Tibetan Plateau with a dense broadband seismic array

Based on observations from a dense broadband seismic array located along the northeastern (NE) margin of the Tibetan Plateau in southeastern Gansu Province,we use receiver functions (RFs) to pick the arrival times of P-to-S converted waves and bin the traces in different grids according to the piercing points of the 410 and 660 km discontinuities in the upper mantle.The depths of the two discontinuities are estimated by the ray tracing method with the IASP91 velocity model and a 3-D tomography model.The results indicate the following:(1) The arrival times of the P410s and P660s converted phases are delayed by approximately 1 s than those predicted by the IASP91 model.The mantle transition zone (MTZ) is thicker than that in the global model.(2) The synchronous lags in the P410s and P660s arrival times are consistent with low-velocity anomalies in the upper mantle,which are believed to result mainly from the eastward migration of materials beneath the NE margin of the Tibetan Plateau.(3) Combined with previous tomography results,the depression of the'660'discontinuity and the thickened MTZ are somewhat consistent with the big mantle wedge (BMW) model.However,due to data limitations,more studies are required to explore the BMW in the future.     

基于生态敏感性和生态系统服务的黑河中游生态功能区划与生态系统管理

生态功能区划是协调生态保护与经济发展的矛盾、实施区域生态系统管理的重要途径。以黑河中游为研究区,基于基础地理信息数据、自然地理数据和土地覆被数据（1986、1995、2000、2010、2011年）,在生态敏感性和生态系统服务重要性分析的基础上,以最小子流域为基本单元,运用二阶聚类法进行生态功能区划;并依据主导生态系统服务对研究区进行分区管理与生态调控。得出结论：（1）黑河中游生态系统类型以荒漠、草地和农田为主,占总面积的90%;森林、水域、城镇与农村居民点零星分布,所占面积不到10%;1986-2010年,农田经历了减少-扩张-再减少的变化,但城镇与农村居民点一直呈现扩张趋势;（2）西北部生态敏感性明显高于东南部,其中极敏感区（约占24%）主要位于张掖-临泽-高台平原北侧、合黎山、祁连山山前戈壁与荒漠、肃南明花区;高度敏感区（约占58%）分布于走廊中部冲洪积平原;（3）各生态系统服务重要性空间分布格局具有一定的相似性,非常重要和极重要综合服务功能区约占3.2%,位于走廊中部的黑河干流缓冲区内;中等和一般重要地区约占20%,分布在山丹和民乐境内祁连山、焉支山、龙首山附近;（4）黑河中游可分为祁连山森林草地生态区、走廊冲洪积平原农田生态区和走廊北部平原灌丛荒漠生态区3个生态区8个生态功能区,依其主导生态系统服务分为生态保育区、生态协调区和生态控制区3类,进而提出了对应的生态系统管理措施。     

海底地震仪远震记录接收函数反演——以南海西南次海盆为例

由于海底环境和海底地震仪(OBS)结构的特殊性,用OBS远震记录进行接收函数岩石圈反演研究因为存在一定的困难,所以还很少见.在深入分析问题的基础上,以国产I-4C型宽频带OBS在南海西南次海盆记录的天然地震为实例,我们将傅里叶变换和小波变换相结合以压制海底地震仪记录中的非平稳干扰,获得了信噪比较高、震相清晰的地震记录,进而成功开展了远震记录的岩石圈结构接收函数反演.主要结论是:(1)OBS接收函数的求取是可行的,关键是压制非平稳干扰.(2)西南次海盆的Moho面埋深为海底下10~12km(地壳厚6~8km),沉积物厚度为1~2km,浅部地壳存在低速区,与沉积物和海底扩张停止后的岩浆喷发产生的岩石碎屑和裂隙有关.(3)在扩张脊中央Moho面上方6~12km存在S波低速区,推测扩张中心可能存在下地壳熔融或岩浆房,在17~30km区间S波速度呈负梯度,我们认为扩张中心更深的地方存在热物质的供给.     

利用接收函数反演青藏高原西部地壳S波速度结构

相对于宽阔的腹地,青藏高原西部南北向宽度仅约600km,却记录了印度和欧亚板块汇聚的深部过程及其响应.本文用22台宽频带流动地震台站在西缘构建了一条南北向探测剖面(~80°E,TW-80试验).利用接收函数反演剖面下方S波速度结构,综合西部已有的宽频带探测结果,分析认为:印度板块向北俯冲可能已到达班公湖—怒江缝合带附近,俯冲过程中下地壳发生榴辉岩化;喀拉昆仑断裂带、班公湖—怒江缝合带、阿尔金断裂带均为切穿地壳的深断裂,莫霍面发生错断;喀拉昆仑断裂带和龙木错断裂带之间的中上地壳没有发现连续的S波低速体,说明可能缺乏解耦层,支持青藏高原西部地壳为整体缩短增厚模式.     

Evaluation of a recently proposed record selection and scaling procedure for low‐rise to mid‐rise reinforced concrete buildings and its use for probabilistic risk assessment studies

This paper evaluates a recent record selection and scaling procedure of the authors that can determine the probabilistic structural response of buildings behaving either in the elastic or post‐elastic range. This feature marks a significant strength on the procedure as the probabilistic structural response distribution conveys important information on probability‐based damage assessment. The paper presents case studies that show the utilization of the proposed record selection and scaling procedure as a tool for the estimation of damage states and derivation of site‐specific and region‐specific fragility functions. The method can be used to describe exceedance probabilities of damage limits under a certain target hazard level with known annual exceedance rate (via probabilistic seismic hazard assessment). Thus, the resulting fragility models can relate the seismicity of the region (or a site) with the resulting building performance in a more accurate manner. Under this context, this simple and computationally efficient record selection and scaling procedure can be benefitted significantly by probability‐based risk assessment methods that have started to be considered as indispensable for developing robust earthquake loss models. Copyright © 2013 John Wiley & Sons, Ltd.     

南海季风爆发的统计动力分析

作者对南海季风爆发作了统计动力分析,即将南海季风爆发前后的高低层风场看成一个整体,并以南海季风爆发日为基准,对风场作了经验正交函数(EOF)分析,得到了以下结论:偏差风场的第一模态反映了高低层东亚夏季风环流在南海季风爆发日前后有剧烈变化,这直接体现了南海季风的爆发,并表明此时大气环流有突变发生;第二、三模态则分别反映了具有5～7天振荡周期的中高纬大气长波活动和亚洲季风区中准双周低频振荡的主要活动区,以及中低纬度大气环流的相互作用;第二模态体现了偏差风场的幅散风部分而第三模态则体现了旋转风部分.     

结构双层多重调谐质量阻尼器(DMTMD)控制策略的鲁棒性评价

基于定义的二类优化目标函数,评价双层多重调谐质量阻尼器(DMTMD)控制策略对漂移频率系数(DFR)摄动的鲁棒性。数值研究表明,使用第二类优化准则设计的DMTMD、双重调谐质量阻尼器(DTMD)和多重调谐质量阻尼器(MTMD)比使用第一类优化准则设计的DMTMD、DTMD和MTMD具有更高的对DFR摄动的鲁棒性。而且,使用第二类优化准则设计的总数为4的DMTMD、DTMD和总数为11的MTMD具有近似相同的对DFR摄动的鲁棒性。     

Using Kolmogorov-Smirnov Statistics to Compare Geostrophic Velocities Measured by the Jason,TOPEX, and Poseidon Altimeters

The Kolmogorov-Smirnov (K-S) test is used to compare probability density functions (PDFs) of geostrophic velocities measured by the TOPEX, Poseidon, and Jason altimeters. Velocity PDFs are computed in 2.5° by 2.5° boxes for regions equatorward of 60° latitude. Although velocities measured by the TOPEX and Jason altimeters can differ, on the basis of the K-S test the velocities are statistically equivalent during the ～200 day period when the satellites followed the same orbit. Full records from TOPEX, Poseidon, and Jason show less agreement, which can be attributed to temporal variability in ocean surface velocities and differing levels of measurement noise.     

���ںӱ�CORS���ĵؿǴ�ֱ�˶��ٶȳ�ģ���о�

???ú??CORS?????????4???GPS????????????GAMIT/GLOBK??????е??????????????????????????????????????????????????????????????????????????3???????????????150 mm??11?′??????????4??????????????????10 mm/a????????溯?????????????????????????????????6′×6′?????????????????????????????????     

纳入政府目标考核 建立有效工作机制——合肥市加强和创新防震减灾社会管理的有益尝试

介绍了合肥市创新防震减灾社会管理机制的基本做法,分析了其成效与不足,提出了进一步加强市县防震减灾社会管理的意见和建议。