focal mechanisms and magnitude distributions of “off-fault” earthquakes
Post on 22-Feb-2016
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Focal mechanisms and magnitude distributions
of “off-fault” earthquakes
David D. Jackson, Yan Kagan, and Qi Wang, UCLA
Stefan Hiemer, ETH Zurich
Focal mechanisms• At each point, assumed moment
tensor is weighted sum of those for nearby earthquakes and fault elements
• Weighting inversely proportional to distance
• For moment tensors on faults, weighting proportional to moment rate on fault element.
Earthquake catalog,
magnitude 4.7+, 1850 -
2009
Representation of larger events as sums of
subevents
Earthquake and fault proximity
Projection of fault surface, and weighting scheme
Focal mechanisms derived from earthquakes and faults,
respectively
Optimization of seismicity/fault weighting and smoothing distance
Magnitude distribution for all quakes, and quakes on faults
Expected size limit depends on time window.
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