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The influence of tectonic regimes on the earthquake size distribution: A case study for Italy
Author(s) -
Gulia Laura,
Wiemer Stefan
Publication year - 2010
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 - 10.1029/2010gl043066
Subject(s) - geology , seismology , focal mechanism , tectonics , seismic hazard , slip (aerodynamics) , thrust fault , physics , thermodynamics
We explore the hypothesis that the relative size distribution of earthquakes, or b‐value, systematically depends on the style‐of‐faulting of seismotectonic zones. Because the b‐value has been shown to be inversely proportional to stress, we expect to find b ( thrust ) < b ( strike‐slip ) < b ( normal ). We test this expectation for the case of Italy. We first of all build a seismotectonic zonation model, consisting of 10 distinct tectonic zones. The faulting style of each zone is then characterized by the summed moment tensor of first‐motion and full‐waveform based focal mechanism. We calculate the b‐value for each zone: the lowest values are obtained for reverse zones (0.75–0.81), highest for the normal (1.09), followed by the strike‐slips (0.9–0.92). Our results suggest that b‐values, which are a critical parameter in all seismic hazard assessments, should be set according to the local faulting regimes. In addition, seismotectonic zonation models should take b‐value variations as one input.