Comparison of length of day with oceanic and atmospheric angular momentum series     

J. Kouba  J. Vondrrák 《Journal of Geodesy》2005,79(4-5):256-268

This is a companion paper to earlier comparisons and study of operational polar motion series, published recently in the same journal. In this contribution, four operational, publicly available, length-of-day (LOD) time series have been compared to the atmospheric angular momentum (AAM) augmented with recent oceanic angular momentum (OAM) data during September 1997–July 2000, using several intervals ranging from 3 days to almost 3 years. Additionally, the LOD of the International GNSS Service (IGS) historical series and a new LOD combination (CMB) were also analyzed. All the six LOD series showed an overall correlation exceeding 0.99 for the complete interval of almost 3 years. Even for the shortest interval of only 3 days, the correlation was still higher than 0.60. The combined AAM + OAM series with inverted barometer corrections always gave the best correlation. The Rapid Service LOD of the International Earth Rotation and Reference Systems Service (IERS) compared the best at all intervals but the shortest one, where the CMB LOD was the best with a correlation of 0.73, followed by both IGS series with a correlation of about 0.71. Prior to all the correlation analyses, in addition to the removal of all the known (conventional) LOD tidal variations with periods ranging from 5.6 days to 18.6 years and lunar fortnightly and monthly oceanic tides, small corrections of lunar fortnightly and monthly tides, semi-annual, annual periodical signals, drift and scale had to be estimated with respect to the combined AAM + OAM series.  相似文献   

一种新的运动检测及轮廓追踪方法   总被引：7，自引：0，他引：7  

吕常魁  姜澄宇  王宁生 《武汉大学学报(信息科学版)》2005,30(8):723-727

构建了基于块区域二阶矩比的三帧差分运动检测模型,应用文献[1]中的核密度估计模型来滤除其中的非运动区域,并采用支持向量聚类实现多目标检测。给出了运动物体轮廓快速追踪的RW算法,该算法不必考虑检测区域内部的细节问题,能够充分利用所检测到的边缘信息,比较符合人眼对轮廓的搜索习惯。最后给出了实验结果。  相似文献   

云南地震数字遥测台网子台地动噪声分析   总被引：6，自引：1，他引：6  

杨晶琼  杨周胜 《地震研究》2005,28(1):86-89

介绍了云南数字遥测台网的基本情况，阐述了地动噪声有效值和功率谱的计算方法。对选取的资料进行预处理后，计算分析了云南数字遥测台网全部子台的地动噪声水平，按地动噪声水平对子台进行了分类。指出了地动噪声分析对台网建设的作用。  相似文献   

断层破碎带对非发震断层场地地震动的影响   总被引：6，自引：0，他引：6  

任春  罗奇峰 《地震研究》2005,28(2):162-166

运用动接触单元对断层场地中的非发震断层的实际运动状态进行了模拟，并结合有限元模型分析了断层场地中非发震断层对场地地震动的影响。通过计算和比较无摩擦力、有摩擦力和无断层三种工况，探讨了动接触单元模拟非发震断层的合理性。计算中还考虑了断层破碎带及断层破碎带土的一些性质，结果表明考虑断层破碎带的存在对于地震动是有影响的。同时还指出，在研究实际非发震断层对场地地震动影响时，应具体考虑场地诸因素的复杂性。  相似文献   

川滇地区现今块体水平运动变形特征分析   总被引：2，自引：0，他引：2  

张晓亮  江在森  王双绪  陈兵  黄国柱 《地震研究》2005,28(3):262-267

依据川滇地区1991，1999和2001年GPS测量数据，利用DDA正分析基本原理，结合现有的地质资料，对该地区近年来的水平构造运动特征进行了模拟分析，认为川滇地区水平运动整体速率在1999～2001年期间明显减弱；川滇决体主压应变以顺时针旋转为主，方向为SE—SEE；其南部是运动变形相对剧烈、易于积累能量的区域；未来一两年内，该地区地震活动水平不会太高。  相似文献   

A method for the interpolation of nonnegative functions with an application to contaminant load estimation     

A. M. Michalak  P. K. Kitanidis 《Stochastic Environmental Research and Risk Assessment (SERRA)》2005,19(1):8-23

The objective of this work is to extend kriging, a geostatistical interpolation method, to honor parameter nonnegativity. The new method uses a prior probability distribution based on reflected Brownian motion that enforces this constraint. The work presented in this paper focuses on interpolation problems where the unknown is a function of a single variable (e.g. time), and is developed both for the case with and without measurement error in the available data. The algorithms presented for conditional simulations are computationally efficient, particularly in the case with no measurement error. We present an application to the interpolation of dissolved arsenic concentration data from the North Fork of the Humboldt River, Nevada.  相似文献   

On a Quick Seismic Microzonation of Wide Areas     

A. Teramo  M. Maugeri  A. Bottari  D. Termini 《Pure and Applied Geophysics》2005,162(4):671-682

In this paper a characterization of seismic site response is proposed, taking into consideration geo-morphological conditions, geotechnical and geophysical parameters such as slope, average shear-wave velocity, maximum expected acceleration on bedrock, depth of ground water table. An empirical relationship is presented between these parameters and applied, with the objective of determining ground motion amplification coefficients to be used in specific programs of land use or town planning dedicated to the mitigation of seismic risk.  相似文献   

Estimation of Site Response in Kachchh,Gujarat, India,Region Using H/V Spectral Ratios of Aftershocks of the 2001 <Emphasis Type="Italic">M</Emphasis><Subscript><Emphasis Type="Italic">w</Emphasis></Subscript> 7.7 Bhuj Earthquake     

Prantik Mandal  R K Chadha  C Satyamurty  I P Raju  N Kumar 《Pure and Applied Geophysics》2005,162(12):2479-2504

Site response in the aftershock zone of 2001 Bhuj M_w 7.7 earthquake has been studied using the H/V spectral ratio method using 454 aftershocks (M_w 2.5–4.7) recorded at twelve three-component digital strong motion and eight three-component digital seismograph sites. The mean amplification factor obtained for soft sediment sites (Quaternary/Tertiary) varies from 0.75–6.03 times for 1–3 Hz and 0.49–3.27 times for 3–10 Hz. The mean amplification factors obtained for hard sediment sites (hard Jurassic/Mesozoic sediments) range from 0.32–3.24 times for 1–3 Hz and 0.37–2.18 times for 310 Hz. The upper bounds of the larger mean amplification factors for 1–3 Hz are found to be of the order of 3.13–6.03 at Chopadwa, Vadawa, Kavada, Vondh, Adhoi, Jahwarnagar and Gadhada, whereas, the upper bounds of the higher mean amplification factors at 3–10 Hz are estimated to be of the order of 2.00–3.27° at Tapar, Chopadwa, Adhoi, Jahwarnagar, Gandhidham and Khingarpur. The site response estimated at Bhuj suggests a typical hard-rock site behavior. Preliminary site response maps for 1–3 Hz and 310 Hz frequency ranges have been prepared for the area extending from 23–23.85 °N and 69.65–70.85°E. These frequency ranges are considered on the basis of the fact that the natural frequencies of multi-story buildings (3 to 10 floor) range between 1–3 Hz, while the natural frequencies for 1 to 3 story buildings vary from 3–10 Hz. The 1–3 Hz map delineates two distinct zones of maximum site amplification (>3 times): one lying in the NW quadrant of the study area covering Jahwarnagar, Kavada and Gadadha and the other in the SE quadrant of the study area with a peak of 6.03 at Chopadwa covering an area of 70 km × 50 km. While the 3–10 Hz map shows more than 2 times site amplification value over the entire study area except, NE quadrant, two patches in the southwest corner covering Bhuj and Anjar, and one patch at the center covering Vondh, Manfara and Sikara. The zones for large site amplification values (∼3 times) are found at Tapar, Chopadwa, Adhoi and Chobari. The estimated site response values show a good correlation with the distribution of geological formations as well as observed ground deformation in the epicentral zone.  相似文献   

Effect of tilt on strong motion data processing   总被引：5，自引：2，他引：5  

Vladimir M. Graizer   《Soil Dynamics and Earthquake Engineering》2005,25(3):197-204

In the near-field of an earthquake the effects of the rotational components of ground motion may not be negligible compared to the effects of translational motions. Analyses of the equations of motion of horizontal and vertical pendulums show that horizontal sensors are sensitive not only to translational motion but also to tilts. Ignoring this tilt sensitivity may produce unreliable results, especially in calculations of permanent displacements and long-period calculations. In contrast to horizontal sensors, vertical sensors do not have these limitations, since they are less sensitive to tilts. In general, only six-component systems measuring rotations and accelerations, or three-component systems similar to systems used in inertial navigation assuring purely translational motion of accelerometers can be used to calculate residual displacements.  相似文献   

A varying time-step explicit numerical inte-gration algorithm for solving motion equa-tion     

周正华  王宇欢  刘泉  尹晓涛  杨程 《地震学报(英文版)》2005,18(2):239-244

Introduction In linear elastic medium,motion equation for lumped-mass finite element simulation of wave motion is expressed as(LIAO,2002)∑=+lililii ttGtM)()()(FUU&&(1)where Mi is lumped-mass at node i,Gil is stiffness coefficient of node i with respect to node l,üi(t)is acceleration vectors at node i,Ul(t)is displacement vectors at node l,Fi(t)is the external nodal force vectors acting at node i.If acceleration vectorsüi(t),displacement vectors Ul(t)and the external nodal force vectors…  相似文献