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On the stress dependence of the earthquake b value
Author(s) -
Scholz Christopher H.
Publication year - 2015
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 - 10.1002/2014gl062863
Subject(s) - lithosphere , differential stress , slab , stress (linguistics) , seismology , subduction , geology , tectonics , geophysics , deformation (meteorology) , linguistics , philosophy , oceanography
Laboratory experiments have shown that the b value in the size distribution of acoustic emission events decreases linearly with differential stress. There have been a number of observations that indicate that this relation may also hold for earthquakes. Here using a simple frictional strength model for stresses in the continental lithosphere combined with earthquake b values measured as a function of depth in a wide variety of tectonic regions, we verify and calibrate that relation, finding b = 1.23 ± 0.06 − (0.0012 ± 0.0003)( σ 1 − σ 3 ), where the stress difference ( σ 1 − σ 3 ) is in megapascal. For subduction zones, we find that b value correlates linearly with the slab pull force and with the net reduction of plate interface normal force, both of which also indicate a negative linear relation between b value and differential stress.