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1.
本文利用南极中山站和新奥尔松(NAL)等5个北极站2000年9月到2003年3月共719天的地磁观测数据,以20 min间隔内地磁北向水平分量的互相关系数大于09为判据,对南北极地磁活动相关的发生率进行了统计,并与T89地磁模型得到的中山站共轭位置的分布进行了比较. 结果表明,南北极地磁活动相关的发生率与台站位置、季节、地方时和地磁活动性有着密切的关系. 在北极的5个台站中朗伊尔站(LYR)与中山站地磁相关的时间最多(占17%);在两分季发生相关的情况比冬季和夏季多;在傍晚发生相关的情况最多,中午发生相关的情况最少;地磁活动较强时,相关的情况比地磁宁静时更多一些. 相似文献
2.
In 2019, four strong earthquakes of Mw>6.4 occurred successively in Mindanao, Philippines. Based on the reports from the USGS and PHIVOLCS, these earthquakes were dominated by strike-slip ruptures. Whether these earthquakes are temporally and spatially related remained unknown. We characterized the coseismic displacement fields during the earthquake sequence using an InSAR technique with Sentinel-1 SAR data. The InSAR deformation measurements convincingly reveal that the four earthquakes produced distinct coseismic displacement patterns. We estimated the source parameters of the earthquakes with a two-step inversion strategy. The optimal model suggests that the earthquake sequence resulted from the reactivation of a conjugate fault structure that involves two nearly vertical left-lateral strike-slip faults and two high-angle right-lateral strike-slip faults. We calculated Coulomb stress changes from the earthquake sequence, suggesting that the previous strong earthquakes had significant stress-encouraging effects on the following events. The regional velocities based on the GPS analysis suggest that the formation of this conjugate structure is mainly due to the westward movement of the subducting Philippine Sea Plate. This earthquake sequence provides a seismotectonic background for subsequent strong earthquakes and helps to better understand the formation mechanisms and seismotectonic implications of conjugate structure rupturing. 相似文献
3.
Few building codes contains provisions fault surface ruptures and accompanying soil deformations which constitutes a great risk to human lives, buildings and infrastructure. A numerical and experimental comparison show a fair agreement of result. Analysis of “real” scale show the how water increases the incompressibility of wet soil causing shear deformations to become larger and conjugate ruptures to appear for reverse faults. Field observations and numerical analysis indicates that horizontal compression of soil surrounding underground structures should be taken into account in design. 相似文献
4.
TheQvaluevariationsinthepreparingpro┐cesofrockruptureBINWANG1)(王彬),ZHAO-YONGXU1)(许昭永),JIN-MINGZHAO1)(赵晋明)YI-LIHU2)(胡毅力)1)Sei... 相似文献
5.
This paper introduces how the ratioR of the characteristic stiffness of rock samplevs. the stiffness of testing machines would influence the rupturing process and the acoustic emission (AE) on the part of the
tested rock samples. Result of the experiment shows: WhenR>0.20, the rock sample would rupture abruptly; whereas whenR<0.20, the rock samples would rupture slowly. When the samples rupture abruptly, the time-dependent variation of the AE rate
takes such a pattern:peak value—stable low values—rises to the maximum value (concentration)—drops back to the minimum value
(quiescence)—(rises again)—ruptures. Moreover, smallerR-value tends to be associated with longer quiescence and vice versa. WhenR>1.50, no pre-failure quiescence is detected. When the rock samples rupture slowly, the variation pattern of the AE rate (after
the stress has increased to more than 50% of the rupturing stress) is as the following:stable low (or high) values—rises (or
drops) to its maximum (or minimum) values and then continues for some time—ruptures.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 223–233, 1991.
This study is supported by the Chinese Joint Seismological Science Foundation. 相似文献
6.
点源三维地电场的求解是一大型数值计算问题.本文用有限差分方法求解,最后形成一个线性方程组Ax=b,这里A是大型稀疏的带状对称矩阵.解大型稀疏方程组的完全Cholesky分解直接算法,一般要求巨大的机器内存来存储系数矩阵A,而且计算速度极慢.因此引入不完全Cholesky共轭梯度(ICCG)算法及按行索引的稀疏存储模式,充分利用A的稀疏性,使得计算速度大大提高,而内存要求则大大减少,因此ICCG算法是地电三维正演的强有力工具. 相似文献
7.
Average slip rate,earthquake rupturing segmentation and recurrence behavior on the Litang fault zone,western Sichuan Province,China 总被引:3,自引:0,他引:3
XU Xiwei WEN Xueze YU Guihua ZHENG Rongzhang LUO Haiyuan & ZHENG Bin . Institute of Geology China Earthquake Administration Beijing China . Earthquake Administration of Sichuan Province Chengdu China 《中国科学D辑(英文版)》2005,48(8):1183-1196
The Litang fault zone (LFZ) is an important active fault within the northwestern Sichuan sub-block. To-gether with the Garzê-Yushu, Xianshuihe, and An-ninghe fault zones on its northern, eastern and south-eastern sides, the LFZ constitutes the lateral extrusion tectonic system in the southeastern part of the Qing-hai-Tibetan Plateau[1,2] (Fig. 1). According to instru-mental records, historical recordings and field investi- gation, an earthquake (Ms7.3) occurred on its middle to south se… 相似文献
8.
付德俊 《物探化探计算技术》2019,(3):365-370
开展了不同观测方式的井地2.5D直流电阻率反演研究。①从2.5维直流电阻率满足的边值问题出发,采用变分原理结合节点线性基函数推导了2.5维井地DC满足的积分弱解形式;②构建了二阶最大平滑稳定泛函的2.5维井地直流电阻率正则化目标函数,采用共轭梯度算法对正则化目标函数进行最优化求解,并采用逐步衰减正则化因子的求解策略来提高反演的稳定性;③设计了均匀半空间模型得到的数值解与解析解对比,电位的相对误差在2%以内,阐述正演算法的正确性和高精度。另外,分析了不同观测装置的2.5维井地直流电阻率异常体特征,并对不同观测方式对2.5维井地DC理论数据进行反演研究。研究结果表明,井中数据的引入提高了2.5DC对纵向探测的分辨率能力,同时提高了2.5DC反演有效性以及准确性。 相似文献
9.
Spherical Radial Basis Functions (SRBFs) can express the local gravity field model of the Earth if they are parameterized optimally on or below the Bjerhammar sphere. This parameterization is generally defined as the shape of the base functions, their number, center locations, bandwidths, and scale coefficients. The number/location and bandwidths of the base functions are the most important parameters for accurately representing the gravity field; once they are determined, the scale coefficients can then be computed accordingly. In this study, the point-mass kernel, as the simplest shape of SRBFs, is chosen to evaluate the synthesized free-air gravity anomalies over the rough area in Auvergne and GNSS/Leveling points (synthetic height anomalies) are used to validate the results. A two-step automatic approach is proposed to determine the optimum distribution of the base functions. First, the location of the base functions and their bandwidths are found using the genetic algorithm; second, the conjugate gradient least squares method is employed to estimate the scale coefficients. The proposed methodology shows promising results. On the one hand, when using the genetic algorithm, the base functions do not need to be set to a regular grid and they can move according to the roughness of topography. In this way, the models meet the desired accuracy with a low number of base functions. On the other hand, the conjugate gradient method removes the bias between derived quasigeoid heights from the model and from the GNSS/leveling points; this means there is no need for a corrector surface. The numerical test on the area of interest revealed an RMS of 0.48 mGal for the differences between predicted and observed gravity anomalies, and a corresponding 9 cm for the differences in GNSS/leveling points. 相似文献
10.