The signature and mechanics of earthquake ruptures along shallow creeping faults in poorly lithified sediments Fabrizio Balsamo et al., NEXT -- Natural and Experimental Tectonics Research Group, Department of Physics and Earth Sciences, Parma University, Parco Area delle Scienze 157A, 43124 Parma, Italy. Published online 21 Mar. 2014; http://dx.doi.org/10.1130/G35272.1.
Earthquakes occur episodically along shallow, creeping faults in poorly lithified sediments. This represents an unsolved paradox, largely due to (1) our poor understanding of the mechanics governing creeping faults and (2) the lack of documented geological evidence showing how coseismic rupturing overprints creeping, stable faults in near-surface conditions. In this paper, Fabrizio Balsamo and colleagues describe the signature of seismic ruptures propagating along shallow creeping faults affecting unconsolidated sediments in the forearc Crotone Basin (south Italy). Field observations of deformation band-dominated fault zones show widespread foliated cataclasites in fault cores, locally overprinted by sharp slip surfaces decorated by thin black gouge layers. Compared to foliated cataclasites, black gouges possess much lower grain size/porosity/permeability and are characterized
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