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101.
Using seismic waveform data recorded at station YK (Yingkou) of Liaoning Telemetry Digital Seismic Network, this paper studied the characteristics of shear-wave splitting before and after the Xiuyan MS5.9 (ML5.3) earthquake in November 29, 1999 with SAM method. The results show that the predominant polarizations of fast shear-waves at YK is in direction of ENE-WSW, consistent with the direction of regional principal compressive stress and also consistent with the direction of the regional tectonic stress field in North China; time-delays increasing before Xiuyan earthquake may shows accumulation of stress before earthquake. The predominant polarizations of fast shear-waves at YK are also related to the spatial distribution of small earthquakes and correlate with the fault strike. The histogram of monthly average polarizations of fast shear-waves shows that polarizations of fast shear-waves also seems to change from two months before the earthquake, but it still needs more data for verification. 相似文献
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mODUCnONSinceRattw(lwn)develoPedthefirstthcoreticalm0dl0ninternaltides,Inandifferentmodlshavebeenpresented.Theearlym0dlssuchastheonescreatedbyCoxandSandstorm(l962),Baines(l973,l982),etal.wereInainlylinear.Itwasnottmtilthe1980'sthatmodelsforstUdvingthenonlinearclertersofintemaltidesbegant0bedeveloPed.ThempicaloneswerethoseProposedorusedbyPinpeeetal.(1984),Maze(l987),WllmottandEdnds(l987),~(l994),andGerkema(l996).klthoughthesemodlscontribuegnailytoourundrstandingofthegenerationandproPag… 相似文献
105.
A layered three-dimensional nonlinear numerical model was constructed to simulate the generation and propagation of internal
tides over the continental slope. The simulation was split into external mode computation (EMC) and internal mode computation
(IMC) to minimize the computational load. IMC was carried out once after EMC was implemented N times. As to EMC, a semi-implicit
numerical scheme was applied in such a way that the pressure gradient terms and the velocity divergence terms were discretized
semi-implicitly, but the other terms were discretized explicitly. Eulerian-Lagrangian explicit discretization was applied
to the convective terms simultaneously. As a result, the stability of EMC did not depend on the wave celerity and time step
was not limited by the CFL condition. More than that, use of the conjugate gradient accelerated Jacobi method further improved
the computational efficiency of the model.
Contribution No. 3588 from the Institute of Oceanology, Chinese Academy of Sciences.
Project 49676275 supported by NSFC and National Special Research Program 97-925-05-02. 相似文献
106.
基于首都圈地震台网2002——2005年的区域地震波形数据,采用剪切波分裂系统分析方法(SAM), 计算得到首都圈东南部地区(38.5deg;N——39.85deg;N,115.5deg;E——118.5deg;E)24个台站的剪切波分裂参数. 结果表明,首都圈东南部地区快剪切波平均偏振方向与区域最大主压应力方向相近,与华北地区GPS主压应变测量结果一致;但首都圈东南部盆地地区的剪切波分裂观测结果与首都圈西北部的隆起——盆地构造结合区的观测结果不同. 这说明了不同的构造对观测结果具有一定的影响. 研究还表明,台站附近的断层分布状态对观测结果影响很大,复杂的断层分布会加剧剪切波分裂测量结果的离散程度. 本研究区域南部台站与北部台站的快剪切波偏振方向存在较大差异,这可能与该区南北部的构造及应力环境存在较大差异有关. 相似文献
107.
低渗透储层水平井-直井联合布井技术具有广泛的应用前景,其布井方式至关重要。首先利用劈分流场的方法直观地给出常规储层水平井-直井联合布井的产能评价方法;然后针对低渗透储层的渗流特点,在考虑启动压力梯度条件下建立新的井网渗流物理模型并求解得到产能评价公式;最后经分析计算给出启动压力梯度影响的面积井网极限注采井距关系曲线。研究结果为低渗透储层部署水平井-直井联合井网提供理论依据。 相似文献
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109.
Temporal changes in shear-wave splitting at an isolated swarm of small earthquakes in 1992 near Dongfang, Hainan Island, southern China 总被引:14,自引:0,他引:14
Yuan Gao Peide Wang Sihua Zheng Ming Wang Yuntai Chen & Huilan Zhou 《Geophysical Journal International》1998,135(1):102-112
An isolated swarm of small earthquakes occurred in 1992, near Dongfang on Hainan Island, southern China. The Institute of Geophysics, State Seismological Bureau of China, monitored the swarm with five DCS-302 digital accelerometers for three months from 1992 June 1. 18 earthquakes, with magnitudes M L ranging from 1.8 to 3.6, were well located by five stations, and shear-wave splitting varying azimuthally was analysed on 27 seismic records from these events. The mean polarization azimuth of the faster shear wave was WNW. Time delays between the split shear waves at two stations varied with time and space. The time delays at one station fell abruptly after earthquakes of magnitudes 3.1 and 3.6, but did not change significantly at the second station. This behaviour is consistent with the delay-time changes being caused by changes in the aspect ratio of vertical liquid-filled (EDA) cracks. Thus, the variation in shear-wave-splitting time delay could be due to changes in crustal stress related to nearby small-magnitude earthquake activity. The connection between earthquake activity and crustal stress variation measured by shear-wave splitting leaves the door open for possible observations of crustal stress transients related to the onset of an earthquake; however, our data cannot be considered as definite evidence for such precursors. 相似文献
110.
本文提出了同步旋转法(ASR)和独立旋转法(AIR)两种算法,用以计算分裂的横波中高速和低速横波之间的时间延迟以及高速模波的极化方向。 相似文献