Bulletin of the Seismological Society of America; August 2006; v. 96; no. 4A;
p. 1241-1256; DOI: 10.1785/0120050164
© 2006 Seismological Society of America
Source Finiteness and Rupture Propagation Using Higher-Degree Moment Tensors
Juan Li1,
Yu-Mei He1 and
Zhen-Xing Yao1
1 Institute of Geology and
Geophysics
Chinese Academy of Sciences
100029, Beijing,
China
juanli{at}mail.iggcas.ac.cn
Higher-degree moment tensor representation of seismic sources is obtained for
a horizontally layered homogeneous medium. A Taylor series expansion of
Greens function around a reference source position and time is made, and
this enables us to approximate the seismic radiation in both the regional and
teleseismic distances through a sequence of terms representing increasingly
detailed aspects of the source behavior. Source coefficients and orientation
factors of the first- and second-degree moment tensors are obtained. The
representation is applied to a unilateral rupture Haskell fault model, and the
synthetic seismograms of different models calculated by the higher-degree moment
tensors are compared with the theoretical solutions for a propagating source.
Our results show that, the representation of higher- degree moment tensors up to
degree 2 can describe the response of a moving source well enough, and
its possible to use the moment series as a tool for calculating
seismograms from finite and propagating faults in the forward sense. The
computation takes much less time than the method of summing point sources over
the fault surface. The information yielded by the higher-degree moments may
solve problems such as the fault-plane ambiguity and the spacetime
evolution of the rupture propagation of an earthquake.
Copyright © 2009 by Seismological Society of America