Inbook,
Seismic Source Theory
4, chapter 4.02, page 59--82. Elsevier, Amsterdam, (2007)
DOI: 10.1016/B978-044452748-6.00061-4
Abstract
We review the foundations of seismic source theory as it is used in
practical studies of individual earthquakes. We first present seismic
radiation from point forces in detail, including seismic waves in
the near and far field and energy balance. Point sources are not
really good models for a majority of earthquakes because earthquakes
are better represented by distributions of seismic moment tensor
(or double layer potentials). We study the Green tensor for a point
moment tensor source clearly separating near and far field terms.
Using the standard Brune's model for the seismic spectrum we derive
expressions for the radiated energy as a function of moment tensor.
The theory of point sources is then used to compute the radiation
of seismic waves from finite sources in the so-called kinematic approximation
in which the slip distribution on the fault is specified in a more
or less arbitrary way. Finally, we study the basics of fracture theory
and a simple dynamic source model, the circular crack embedded in
a uniform elastic medium.
