Far-field radiated energy scaling in elastodynamic
earthquake fault models
Shaw BE
BULLETIN OF THE SEISMOLOGICAL SOCIETY OF AMERICA
88: (6) 1457-1465 DEC 1998
Abstract:
Measurements of the far-field radiated energy in very
simple elastodynamic fault models is presented, and the scaling of the
radiated energy with moment and rupture length is examined. The models
produce a complex sequence of events having a wide range of sizes as a
result of a frictional-weakening instability. Thus, radiated energy from
a broad range of sizes of events can be measured. Using conservation of
energy, I am able to measure the far-field energy very accurately and efficiently.
I study a range of frictions, from velocity weakening to slip weakening,
in order to examine the effects of the physics of the rupture source on
the radiated energy, Examining the scaling of radiated energy as a function
of moment and rupture length, I find differences for slip-weakening as
compared to velocity-weakening friction. I find distinct differences in
how the apparent stress scales with moment and also how the apparent stress
divided by the stress drop scales with moment for the different frictions.
Most dramatically, the apparent stress divided by the stress drop is significantly
smaller for slip weakening relative to velocity weakening. This suggests
that measurements of radiated energy versus moment and rupture length in
earthquakes, combined with forward elastodynamic modeling, can be used
to constrain possible source physics.