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991.
992.
We study the effects of structural inhomogeneity on the quasi-static growth of strike-slip faults. A layered medium is considered, made up of an upper layer bounded by a free surface and welded to a lower half-space with different elastic property. Mode III crack is employed as a mathematical model of strike-slip fault, which is nucleated in the lower half-space and then propagates towards the interface. We adopt FEM-β, newly proposed analysis method for failure, to simulate the quasi-statistic crack growth governed by the stress distribution in layered media. Our results show that along planar traces across interfaces a compliant upper layer has significant effects on promoting/suppressing crack growth before/after its extension into the layer and vice versa for a rigid one. This proposes a possibility that surface breaks due to strike-slip faulting could be arrested by deposit layers at the topmost part of the Earth's crust. 相似文献
993.
994.
995.
Waveform inversion in the Laplace domain 总被引:12,自引:0,他引:12
996.
Non-parametric seismic data recovery with curvelet frames 总被引:12,自引:0,他引:12
997.
The dynamic coalescence of two mode II cracks on a planar fault is simulated here using the elastodynamic boundary integral equation method. We focus on the complexity of the resultant slip rate and seismic radiation in the crack coalescence model (CCM) and on the reconstruction of a single crack model (SCM) that can reproduce the CCM waveforms from heterogeneous source parameters rather than coalescence. Simulation results reveal that localized higher slip rates are generated by coalescence as a result of stress interaction between the approaching crack tips. The synthesized seismic radiation exhibits a distinct coalescence phase that has striking similarities to stopping phases in the radiation and propagation properties. The corresponding SCM yields a singular increase in the stress drop distribution, which is accompanied by a sudden decrease in it across the point of coalescence in the CCM. This implies that the generation of high-frequency radiation is more efficient from coalescence than from stopping, although both phenomena exhibit the same strong ω−2 -type displacement spectra. 相似文献
998.
Instantaneous deformation from continuous GPS: contributions from quasi-periodic loads 总被引:3,自引:0,他引:3
Richard A. Bennett 《Geophysical Journal International》2008,174(3):1052-1064
Continuous GPS (CGPS) coordinate time-series are known to experience repeating deformation signals with seasonal and other periods. It is unlikely that these signals represent perfect sinusoids with temporally constant amplitude. We develop an analysis method that accommodates temporal variations in the amplitudes of sinusoidal signals. We apply the method to simulated coordinate time-series to numerically explore the potential consequences of neglecting decadal variation in amplitude of annual motions on the residual-error spectra of CGPS measurements, as well as potential bias in estimates for secular site velocity. We find that secular velocity bias can be appreciable for shorter time-series, and that residual-error time-series of longer duration may contain significant power in a broad band centred on semi-annual frequency if temporal variation in the amplitude of annual motions is not accounted for in the model used to reduce the observations to residuals. It may be difficult to differentiate the bandpass filtered signature of mismodelled loading signals from power-law noise, using residual-error spectra for shorter time-series. We provide an example application to a ∼9-yr coordinate time-series for a CGPS station located in southern California at Carbon Creek Control Structure (CCCS), which is known to experience large amplitude seasonal motions associated with the Santa Ana aquifer system. 相似文献
999.
1000.
针对大庆长垣F油层储层具有孔隙度小、渗透率低、泥质含量高、微孔隙发育、束缚水饱和度高等特点,通过理论和实验分析长垣F油层低孔、低渗储层的主要导电因素,得出泥质附加导电和束缚水导电是该区F油层的低孔、低渗泥质砂岩储层的重要导电因素.考虑束缚水和可动水导电路径不同,基于三水导电模型的推导原理,建立混合水等效电导率方程;依据该区矿化度较低和含泥高的储层特征,对适用于淡水高泥储层的印度尼西亚方程进行改进,用混合水等效电导率代替原方程中的地层水电导率,建立长垣地区F油层低孔低渗泥质砂岩含水饱和度模型.利用岩心分析数据和常规测井资料,采用多元回归法确定长垣F油层饱和度模型中的泥质体积分数、孔隙度、束缚水饱和度.利用岩电实验数据,采用最优化方法确定长垣F油层饱和度模型中的饱和度指数、胶结指数等参数.经密闭取心井含水饱和度对比和试油结果验证,建立的含水饱和度模型可用于F油层的低孔低渗泥质砂岩储层定量评价. 相似文献