论文部分内容阅读
在19和20世纪,地震观测者主要记录地震引起的平移波场,而缺乏对旋转运动的观测和研究。我们的目的是进一步认识地面旋转运动及其与平移波场的关系,着重研究离震源几个波长的近场,在那里可能需要考虑与旋转运动有关的破坏。通过收集大量已公布的强旋转运动数据,得到了一幅包括可获得的旋转振幅及其变化值的基本图件。为了得到更加详细的图件,我们对在格勒诺布尔谷发生的一个走滑型地震进行了大规模的三维数值研究,通过对那里的地形、震源和场地效应相结合,从而产生了逼真的波场。根据旋转和平移的峰值振幅,以及它们与土壤非线性和震源方向性这两个影响因素的关系,分析了合成数据集。在软土层上测得MW6.0级地震的峰值旋转运动量是1mrad,峰值旋转速率是10mrad/s。这些值很大程度上依赖于震源位置、场地条件和地形特征,这些因素会导致20km内的值发生几乎一个数量级的变化。最后,我们利用峰值地面速度(PGV)和峰值地面旋转量(PGω),对数值模拟的结果和类似条件下通过台阵技术得到的野外资料(帕克菲尔德)进行对比,以研究浅源中等大小地震在近场所预期的平移与旋转运动振幅的关系。我们的数值模拟的结果与过去研究中的观测值拟合良好。再有,PGV/PGω比值的空间变化呈现出一个趋势,而这个趋势与研究所选择模型的速度结构有关。
In the 19th and 20th centuries, earthquake observers mainly recorded the translational wave field caused by earthquakes, but lacked the observation and study of rotational movement. Our goal is to further understand the ground-gyroscopic motion and its relationship with the translating wavefield and focus on the near-field at several wavelengths away from the source, where the perturbations associated with rotational motion may need to be considered. By collecting a large number of published strong rotational motion data, a basic map including the available rotational amplitudes and their variations is obtained. In order to get more detailed maps, we conducted a large-scale three-dimensional numerical study of a strike-slip earthquake in the Grenoble Valley by creating a combination of topography, source and site effects there, producing a realistic Wave field. Based on the relationship between peak amplitudes of rotation and translation, and their relationship with soil nonlinearity and source orientation, the synthetic data set is analyzed. The peak rotational motion of MW6.0 earthquake measured on soft soil is 1 mrad and the peak rotation rate is 10 mrad / s. These values are strongly dependent on the source location, site conditions and topography characteristics, which can cause almost one order of magnitude change in values within 20 km. Finally, we compare the results of numerical simulations with field data obtained by array technology (Parkfield) under similar conditions using peak ground velocity (PGV) and peak ground rotation (PGω) to study the effects of shallow-to-medium magnitude earthquakes The expected translational and rotational amplitude of motion at near field. The results from our numerical simulations fit well with the observations from past studies. Again, the spatial variation of the PGV / PG? Ratio shows a trend that correlates with the velocity structure of the model chosen by the institute.