Statical and dynamical study on faulting mechanism of the 1923 Kanto earthquake.
Statical and dynamical study on faulting mechanism of the 1923 Kanto earthquake.
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1923年关东地震断裂机制的静态和动态研究。
DOI：
10.4294/jpe1952.28.119
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发表时间：
1980
期刊：
影响因子：
--
通讯作者：
R. Sato
中科院分区：
文献类型：
--
作者：
M. Matsu'ura;T. Iwasaki;Yasunori Suzuki;R. Sato
推广了一种基于随机误差的大地测量数据求最优故障参数的逆方法，使其适用于包含参考点运动引起的系统误差的三角测量数据。将新的反演方法应用于1923年关东地震的静态位移资料，得到了一个能充分解释地震学和大地测量资料的位错源模型。根据大地测量资料，发现关东地震的断层运动是一个向N24°E倾斜25°的平面上的4.8m的反向右侧滑动，滑移角为140°，其中滑移角从断面上的走向逆时针方向测量。确定断层长度为95km，断层宽度为54km，断层上缘深度为1.5km。估计本次地震的地震矩和应力降分别为8.4×1027达因·cm和45巴。以静态断层解为基本模型，利用东京本古地区的长周期地震记录，研究了断裂的动态过程。结果表明，该断裂始于北经35.41°、东经139.22°、深度13.5km的重新定位震源，并在断面上向外延伸，断裂前缘传播速度为2.0km/sec。假设源时间函数的上升时间为5.0秒。通过将经验公式应用于计算的地面位移，估计东京地区频率范围为0.0-3.3Hz的最大加速度振幅在水平分量上约为280加仑，在垂直分量上约为60加仑。
An inverse method to find optimum fault parameters from geodetic data with random errors is extended so as to be applicable to a case of the data including a systematic error caused by movements of reference points in triangulation. Application of the new inverse method to static displacement data associated with the Kanto earthquake of 1923 yields a dislocation source model which adequately explains both the seismological and the geodetic data.From the geodetic data, it is found that the fault motion of the Kanto earthquake is a reverse, right-lateral slip of 4.8m with a slip-angle of 140° on a plane which dips 25° towards N24°E, where the slip-angle is measured counterclockwise from a strike on the fault plane. The fault length, width, and the depth to the upper fault margin are determined as 95km, 54km, and 1.5km respectively. The seismic moment and stress drop of this earthquake are estimated to be 8.4×1027 dyne·cm and 45 bars, respectively.Taking the static fault solution as the basic model, the dynamic process of the fracture is investigated on the basis of the long-period seismograms recorded at Hongo, Tokyo. The result shows that the rupture starts from a relocated hypocenter, 35.41°N, 139.22°E and 13.5km (depth), and extends outwards on the fault plane with a propagating velocity of the rupture front of 2.0km/sec. The rise time of the source time function is assumed to be 5.0sec. The maximum amplitude of acceleration for a frequency range of 0.0-3.3Hz at Tokyo is estimated to be about 280gal for the horizontal component and to be 60gal for the vertical component, by applying an empirical formula to the calculated ground displacements.