GPS卫星运动状态算法及其软件实现

确定卫星的位置和速度是GPS定位导航的基础,以二体问题为基础,介绍了卫星运动状态的计算方法,建立了计算卫星实时位置、速度的数学模型,并运用C 语言实现了算法,证实了算法的正确性。     

A multi-scale 3-D crust velocity model in the Hefei-Chao Lake area around the southern segment of Tanlu Fault Zone

Regional high-precision velocity models of the crust are an important foundation for examining seismic activity, seismogenic environments, and disaster distribution characteristics. The Hefei-Chao Lake area contains the main geological units of Hefei Basin, with thick sediments and the Chao Lake depression. Several major concealed faults of the southern NNE-trending Tanlu Fault Zone cross this area. To further explore the underground distribution characteristics of the faults and their tectonic evolutionary relationship with adjacent tectonic units, this study used ambient noise data recorded by a seismic array deployed in Hefei City and Chao Lake, constructing a 3-D velocity model at the depth of 1–8 km. Then a multi-scale high-resolution 3-D velocity model of this area was constructed by this new upper crustal velocity model with the previous middle and lower crustal model. The new model reveals that a high-velocity belt is highly consistent with the strike of the Tanlu Fault Zone, and a low-velocity sedimentary characteristic is consistent with the Hefei Basin and Chao Lake depression. The distribution morphology of high and low velocity bodies shows that the sedimentary pattern of Hefei-Chao Lake area is closely related to the tectonic evolution of the Tanlu Fault Zone since the Mesozoic. This study also identifies multiple low-velocity anomalies in the southeastern Hefei City. We speculate that strong ground motion during the 2009 Feidong earthquake (magnitude of 3.5) was related to amplification by the thick sediments in the Hefei Basin. We also discuss further applications of multi-scale high-resolution models of the shallow layer to strong ground motion simulations in cities and for earthquake disaster assessments.     

太湖水体中悬浮物的静沉降特征

本文分别采用斯托克斯沉降速率公式和重复深度吸管法计算了2005年4月、5月间在太湖进行的四次静沉降模拟实验中的沉降速度．结果表明：1)太湖水体中悬浮物的沉降属于絮凝沉降．2)水体中悬浮物浓度与沉降时间均呈现出明显的指数衰减规律(R~2＞0．80),悬浮物中无机物含量较高时这种规律更为明显(R~2≥0．99)．3)悬浮物浓较低时,太湖悬浮物的沉降速率与水体中的悬浮物浓度无明显的相关关系;而悬浮物浓度较高时,沉降速率随悬浮物浓度升高而增大．经拟合沉降速度(ω)与悬浮物浓度(C)之间符合Logistic曲线ω=0．021/(1 exp(-0．026(C-166．3))),R~2=0．98,n=54．4),斯托克斯公式可用来粗略估算太湖悬浮物的沉降速率,而重复深度吸管法则适合于较精确地计算太湖悬浮物的沉降速率．但在计算时须注意根据悬浮物的特性,选取其特征沉降速率．本文计算得到的太湖悬浮物的沉降速率范围为0．002 cm/s-0．005 cm/s．     

汶川地震前后波速比变化特征的再研究

收集整理了四川省地震台网1990—2012年产出的地震直达波震相数据, 利用单台多震和达法对2008年汶川M_S8.0地震前后四川地区的波速比变化特征进行了分析研究(共筛选出13个数据量较为丰富、 连续性较好的台站). 结果显示： 其中位于龙门山断裂中北段西侧的4个台站, 震前出现长达7年左右的中长期波速比低值异常; 其它9个台站的波速比震前变化基本稳定. 震前波速比出现异常的4个台站的分布与汶川M_S8.0地震孕震区范围大体一致, 从而为研究汶川M_S8.0地震前是否存在地壳介质特性的时间变化过程, 提供了有力的判定依据.     

用DSS资料研究首都圈地区的地壳结构

利用几种不同的一维反演方法对天津-北京-赤城剖面的DSS（deep seismic sounding）数据进行了处理．结果显示：沿剖面基底面北浅南深,但C界面和M界面北深南浅,存在镜像关系：地壳平均速度华北盆地较低,燕山下方较高;燕山隆起和华北盆地的交界处曾多次发生过5．0级以上地震。且在该过渡带上,多条深大断裂成北北东、北东向穿过该剖面,推断首都圈地区地震的发生与莫霍面的局部隆起、速度结构的急剧变化以及深大断裂的存在具有密切关系。     

浅水多波束系统SONIC 2024在码头测深中的应用

文中介绍浅水多波束系统SONIC 2024的技术优点,从姿态参数校正、潮汐改正、声速改正、测线滤波及曲面滤波等方面探讨多波束数据处理的关键技术。以码头实测数据验证该系统在水深测量应用中的便捷性和可靠性。     

南海北部新生界地层的远偏移距折射波速度特征

南海北部为张裂大陆边缘,在新生代时期经历了复杂的地质演化,具有良好油气勘探前景.本文首次利用南海北部某区域长排列地震数据的远偏移距折射波速度计算方法获得南海北部地层层速度,并进行了分析,此外,还提出了非初至折射波的概念.本方法在共偏移距剖面上识别、拾取折射波层位,得到折射波走时的横向连续变化数据,利用不同共偏移距同一折射波层位的到达时差计算该折射层位的速度结构.该方法在南海北部陆坡某区域地震资料的应用,揭示了新生界地层层速度的整体结构,反映了新生代不同时代地层的速度变化特征,为进一步利用折射层速度资料探讨南海新生代地质演化提供了新的视角.研究表明,与常规初至折射波法相比,远偏移距折射波能够提供更多的地质信息;该方法的初步应用能够对远偏移距折射波的研究提供进一步的视角.     

VELOCITY CHARACTRISTICS OF SHANXI AND ADJACENT AREA AND ITS TECTONIC SIGNIFICANCE

In order to acquire a better velocity structure of the crustal and uppermost mantle beneath Shanxi area, we obtain the group and phase velocities of Rayleigh wave of the periods 8s to 50s in Shanxi and adjacent area using ambient seismic noise recorded at 216 broad-band stations. All available vertical-component time series for 2014 have been cross-correlated to yield estimates of empirical Rayleigh wave Green's function. Group and phase velocity dispersion curves for Rayleigh wave are measured for each interstation path by applying frequency-time analysis. It describes finer velocity structure of the crust and upper mantle in Shanxi, which reflects the geological structure characteristics at different depths. The resolution is within 50km and the resolution of part periods can reach 40km.The Rayleigh wave group and phase speed maps at short periods(8~18s and 10~22s)show clear correlations with shallow geological structures. Mountain areas on both sides of Shanxi depression zone show apparent high-velocity anomaly, except for low-velocity anomaly in the Taiyuan Basin, Linfen-Yuncheng Basin and Weihe Basin. Especially, the areas of Youyu County-Pianguan County-Kelan County-Shuozhou City and Jingle County-Lishi District of Lüliang City in Lüliang Mountains, and Yu County-Fuping County-Yi County and Yangcheng County-Licheng County in Taihang Mountains, present higher velocity anomaly. In addition, the velocity is lowest in the Weihe Basin, and the amplitude of low velocity decreases gradually from the south to the north of the basins in Shanxi, which probably is related to the process of gradual stretching and development of the Shanxi rift zone from the southwest to the northeast. The obvious velocity difference across the latitude of 38°N exists at 18~30s period of phase and 24~35s period of group velocity maps, which is probably related to the deep and shallow Moho depth variation in the south and north of Shanxi and the suture zone of ancient blocks including "hard" southern block and "soft" northern block. At the same time, the research result of receiver function reveals that partial melting of the lower crust occurs in the northern Taihang Mountains, while the southern section remains stable(Poisson's ratio is above 0.3 in the northern Taihang Mountains and 0.25~0.26 in the southern section). The phase velocity map at 30~50s period clearly shows NW velocity gradient belt, and the low velocity anomaly in the northeast side may be related to Cenozoic volcanism. Meanwhile, the eastern border of Ordos block is the western faults of central basins in Shanxi depression zone. However, some research results indicate that the above border is Lishi Fault in the surface, inferring that the Ordos block shows a shape of wide in the upper and narrow in the lower part from the surface to deep. The Datong volcanic area at 18~45s period of phase and 24~35s period of group velocity maps shows low velocity of trumpet shape from shallow to deep, related to the upwelling of hot material from lower mantle in the Cenozoic causing a large area of intense magmatic activity. It indicates the more specific upwelling channel of Datong volcanoes simultaneously.     

两次降雪天气过程预报中边界层风廓线雷达资料的应用

通过分析2009年10月31日至11月1日和2009年11月9-10日北京两次不同类型降雪天气过程中海淀边界层风廓线仪数据发现:①降雪开始前2h内底层偏东气流建立,且该气流里均有风速突然加强的现象,这对短时临近预报中预报降雪的起始时间有一定参考价值;②700 hPa以上出现冷平流或者冷平流加强且高度降低,也是降雪即将开始的一个特征;③风廓线资料计算得到的温度平流廓线可以较好的反应大气稳定度情况,为判断降雪是否为对流性降雪提供可靠依据.在临近预报中加强风廓线和温度平流的监测,对临近转折性天气的预报有指示意义.     

南海北部东沙运动的构造特征及动力学机制探讨

南海北部陆缘在南海扩张结束后发生了一次重要的构造运动—东沙运动.因前人对其研究较少,目前对其发生时间、影响范围和形成机制等都存在较大的争议.通过对东沙海区及其邻区新近纪地层二维、三维地震资料的详细解释,确定了东沙运动发生在晚中新世晚期,并在晚中新世末/早上新世初(5.5Ma)停止活动.东沙运动主要波及东沙隆起和潮汕坳陷地区,构造上主要表现为断块升降,其中隆起区沉积物遭受剥蚀,造成中新世及部分上新世地层的缺失.这次运动还形成了大量次级的NW-NWW向张性、张扭性断裂,构造运动整体上具有东强西弱的特点.东沙运动可能与新近纪以来菲律宾海板块持续向NWW方向运动导致的吕宋岛弧与欧亚大陆在9～6Ma期间开始发生的弧陆碰撞有关.同时,由于南海向马尼拉海沟下的俯冲及洋壳的冷却沉降作用,南海北部陆缘处于拉张环境,岩浆底侵到下地壳底部形成高速层,破坏了该区域的地壳均衡,从而造成上部地壳的隆升.