Dissipation of Energy Radiated by Earthquakes

Abstract

SUMMARY. - Representing radiated seismic energy as a sum of normal modes
we are able to develop approximate equations describing the dissipation of
this energy in the earth by solid friction. In particular we calculate total energy
radiated and spherically averaged dissipation as a function of depth. In a
sample (long period) model study we find that energy density as a function of
radius and frequency have simple forms and smooth variations with source
depth and mechanism as long as the event's spectrum is dominated by fundamental
mode energy. Further, we find that shallow focus events are an order of
magnitude more energetic than deeper events for the same moment and that
dip slip events are up to a factor of six more energetic than strike slip events for
the same moment and depth.