Scaling Law Of Global Parameters For The Hybrid Source Model From NGA Data

In order to synthesize ground motion at near field from large earthquake, theresearch team headed by the author’s supervisor developed a finite fault based hybridsource model in a dozen years. A set of empirical relationship and semi-empiricalrelationship developed between source parameters and moment magnitude, could beadopted in estimation the general characteristics and the slip distribution on the ruptureplane of a future large earthquake, among them the scaling laws of global sourceparameters were developed statistically from data of158earthquakes world wide inthree rupture types and in three magnitude intervals. Two years later, NGA (NextGeneration Attenuation) project released a database of strong ground motion with3551records of173earthquakes world wide, and source parameters such as rupture planewidth, area, length and average slip on the plane were available for62quakes amongthem. In2013, a new NGA database was further released with21539records of607earthquakes, and source parameter of77quakes among them were available. Theexisting data of the team are checked and supplied with the two NGA databases, then aset of new scaling law of global source parameters are developed. By means ofcomparison of three sets of data and corresponding scaling laws, of three sets of30source models respectively for each set built for an earthquake with magnitude7.0, ofcomparison of ground motion synthesized randomly, the stability and applicability oforiginal scaling laws are discussed and verified in this dissertation. The main progressesare as follows.1. Source parameters of31in the existing158earthquakes are revised and sourceparameters of31and46quakes are supplied respectively from the two NGA databases,then two new data sets are worked out as data1and data2. The differences between thegeneral characteristics of the data sets after so large an update are analyzed in detail, andnecessity of further inspection is shown.2. Two new sets of scaling laws of global source parameters of the hybrid sourcemodel in tree earthquake rupture types, all, strike-slip and dip-slip, and three magnitudeintervals (4.5,6.5],(6.5,7.0],(7.0,7.9or7.6], are developed statistically, includingempirical relations and semi-empirical relations between rupture plane width, area,length and average slip on the plane and moment magnitude. The results of comparisonof the relations and the existing relation show a fact that the difference between them isnot obvious and the dispersion of data around the relations is reduced in some degreefrom increasing of data amount.3. By means of two new scaling laws and existing one, three sets of30sourcemodels respectively for each set are built for an earthquake with magnitude7.0on anactive fault in North-western China. Combining with exploration results of the activefault, three sets of the mean and standard deviation of width, area, length the rupture plane and average slip on the plane are estimated in order. Global parameters of30source models for each set are generated by substituting the means and standarddeviations into truncated Normal Distribution and slip distributions of those models arethen generated with the values of local source parameters from the existing scaling lawstogether.4. High frequency ground motions at4sites in near field from each source modelare synthesized randomly. Difference between ground motions from three sets of sourcemodels by the two new scaling laws and the existing one are compared on accelerationtime histories, response spectra and peak acceleration values. The results show that thenew scaling laws improve the estimations of response spectra and peak acceleration insome degree, but no obviously.