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Mapping b‐values in France using two different magnitude ranges: Possible non power‐law behavior
Author(s) -
Beauval Céline,
Scotti Oona
Publication year - 2003
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 - 10.1029/2003gl017576
Subject(s) - magnitude (astronomy) , power law , geology , range (aeronautics) , seismology , statistics , mathematics , physics , materials science , astronomy , composite material
The first step in probabilistic seismic hazard assessment is the characterization of seismic sources. The fundamental assumption is that the Gutenberg‐Richter power law can be applied and is valid at all scales. In this study, we found that the power‐law model may not be verified in the southeastern regions of France. Frequency‐magnitude distributions are mapped using 2 different magnitude ranges: (1) [3.0–4.4] using only homogeneous instrumental data, (2) [3.5‐M max (observed)] using instrumental and historical data. b‐values estimated on these two magnitude ranges are similar in the Pyrenees and the Rhine Basin. However, they differ significantly in the Southern Alps: the slopes estimated on magnitude range [3.0–4.4] are much steeper (b > 1.4) than the slopes estimated on magnitudes above 3.5 (0.9 < b < 1.1). Until a clear identification of the underlying processes is made, a conservative option (i.e., lowest b‐values) should be considered for probabilistic estimation of hazard in the eastern part of France.