Finite Fault Source Model For Predicting Near-field Strong Ground Motion

Study on strong ground motion is a key research field in the intercross area of engineering and earth science, and is also an urgent requirement of ensuring stabilization and progress of mankind society & reducing earthquake disaster. A lot of investigation and statistic result of earthquake disaster show that casualty and economic losses are both mainly from the damage and collapse of buildings and other engineering structures that are further mainly caused by strong ground motion. Strong ground motion is also an inducing factor of other earthquake destructiveness, such as ground failure, landslip, and so on.In the past ten odd years, strong ground motion records were accumulated very much faster than before. The research results from motion records that were obtained in one earthquake, covered quite large area with a certain density, show the fact that ground motion is not only affected by local site condition, but also governed by spatial distribution of slip and the rupture process on the source plane. In general, it is believed that the empirical attenuation relationships widely adopted in China are too simple and cannot describe the engineering features of the motion very well at near field during strong earthquake, but the finite fault model FFM can do it better. The most difficult problem at present on FFM is how to estimate the in inhomogeneous distribution of slip before an earthquake, and the progress is quite slow.In this paper, a FFM, rectangle finite fault grid model based on kinematics, is adopted after a comprehensive review of plentiful published literatures, the creative achievements are integrated into a specific FFM for predicting near field strong ground motion, and formed a set of doable and applied engineering approach by combined the model with stochastic synthesis of ground motion, in order to satisfy urgent requirement from the project of exploration the assessment of earthquake active fault in urban areas in China, by means of the following three hard works.1. The quantitative scaling laws between global parameters of FFM and moment magnitude are studied in detail while other methods such as remote sensing image recognition, seismo-tectonic investigation, study of aftershock distribution, et al., are summarized. The most systemic database of destructive earthquake source parameters so far is checked and supplemented, analysis methods on relationships between faulting size parameters and moment magnitude are improved from the inherent trends in the data, and a relationship between average slip on the fault planeIVABSTRACTand moment magnitude is established, in this paper, in order to overcome the disadvantages in application of the empirical relationships derived from various source data by some researchers separately, such as the difficulty to express the constraint between each other of some source parameters and the difficulty from different earthquake magnitude scales.(1) The seismic source parameter data of 149 history earthquake world wide from the database by Wells and Coppersmith (1994) are selected, the moment magnitude in the database are corrected by Hanks and Kanamori (1979)'s formula, in addition, the source parameter data of 9 earthquakes since 1993 are supplemented. The relationships between fault size parameters on the fault plane and moment magnitude, and between the average slip on the fault plane and moment magnitude, are systemically studied, and a set of doable and applied scaling laws are worked. The theoretic relationships are simplified to a uniform form log7=aMw-Cy, in which Yis for fault rupture area if o=1.0, but Y for fault rupture length, width or average slip, if a=0.5, Cy is corresponding constant.(2) The different Cy values in the above mentioned equation for different magnitude intervals mean that the limitation on intercept is unbent while the slope is constrained as 1.0 or o.5, from the inherent trend in the data. This subsection of moment magnitude is better to match the data, and to express some physical constraints, for example, rupture...