Mechanical basis for slip along low-angle normal faults
| Autor: | Emmanuel Lecomte, Olivier Lacombe, Laetitia Le Pourhiet |
|---|---|
| Rok vydání: | 2012 |
| Předmět: |
geography
Extensional fault geography.geographical_feature_category 010504 meteorology & atmospheric sciences Slip (materials science) Fault (geology) 010502 geochemistry & geophysics 01 natural sciences Detachment fault Geophysics Brittleness Shear (geology) Fault gouge General Earth and Planetary Sciences Fault mechanics Geology Seismology 0105 earth and related environmental sciences |
| Zdroj: | Geophysical Research Letters. 39 |
| ISSN: | 0094-8276 |
| DOI: | 10.1029/2011gl050756 |
| Popis: | [1] The existence of active low-angle normal faults is much debated because (1) the classical theory of fault mechanics implies that normal faults are locked when the dip is less than 30° and (2) shallow-dipping extensional fault planes do not produce large earthquakes (M > 5.5). However, a number of field observations suggest that brittle deformation occurs on low-angle normal faults at very shallow dip. To reconcile observations and theory, we use an alternative model of fault reactivation including a thick elasto-plastic frictional fault gouge, and test it at large strain by the mean of 2D mechanical modeling. We show that plastic compaction allows reducing the effective friction of faults sufficiently for low-angle normal faults to be active at dip of 20°. As the model predicts that these faults must be active in a slip-hardening regime, it prevents the occurrence of large earthquakes. However, we also evidence the neoformation of Riedel-type shear bands within thick fault zone, which, we believe, may be responsible for repeated small earthquakes and we apply the model to the Gulf of Corinth (Greece). |
| Databáze: | OpenAIRE |
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