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Stress drop with constant, scale independent seismic efficiency and overshoot
Author(s) -
Beeler N. M.
Publication year - 2001
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2001gl012906
Subject(s) - drop (telecommunication) , mechanics , seismic moment , slip (aerodynamics) , stress (linguistics) , geology , physics , fault (geology) , seismology , engineering , thermodynamics , telecommunications , linguistics , philosophy
To model dissipated and radiated energy during earthquake stress drop, I calculate dynamic fault slip using a single degree of freedom spring‐slider block and a laboratory‐based static/kinetic fault strength relation with a dynamic stress drop proportional to effective normal stress. The model is scaled to earthquake size assuming a circular rupture; stiffness varies inversely with rupture radius, and rupture duration is proportional to radius. Calculated seismic efficiency, the ratio of radiated to total energy expended during stress drop, is in good agreement with laboratory and field observations. Predicted overshoot, a measure of how much the static stress drop exceeds the dynamic stress drop, is higher than previously published laboratory and seismic observations and fully elasto‐dynamic calculations. Seismic efficiency and overshoot are constant, independent of normal stress and scale. Calculated variation of apparent stress with seismic moment resembles the observational constraints of McGarr [1999].