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On the geometric complexity of earthquake focal zone and fault systems: A statistical study

Yan Y. Kagan

Published 2009, SCEC Contribution #1256

We discuss various methods used to investigate the geometric complexity of earthquakes and earthquake faults, based both on a <br/>point-source representation and the study of interrelations between earthquake focal mechanisms. We briefly review the seismic <br/>moment tensor formalism and discuss in some detail the representation of double-couple (DC) earthquake sources by normalized <br/>quaternions. Non-DC earthquake sources like the CLVD focal mechanism are also considered. We obtain the characterization of the <br/>earthquake complex source caused by summation of disoriented DC sources. We show that commonly defined geometrical fault barriers <br/>correspond to sources without any CLVD component. We analyze the CMT global earthquake catalog to examine whether the focal <br/>mechanism distribution suggests that the CLVD component is likely to be zero in tectonic earthquakes. Although some indications <br/>support this conjecture, we need more extensive and significantly more accurate data to answer this question fully. <br/>

Citation
Kagan, Y. Y. (2009). On the geometric complexity of earthquake focal zone and fault systems: A statistical study. Physics of the Earth and Planetary Interiors, Phys. Earth Planet. Inter., 173(3-4),, 254-268.