Geometrical and Mechanical Factors Controlling Fault Growth and Seismogenic Ruptures: Natural Cases Through Analogue Models
Abstract
Improved monitoring tools led to unprecedented geometrical characterization of active faults responsible for recent earthquakes (see for instance the last two largest earthquakes in Italy: the 2009 L'Aquila and the 2012 Emilia seismic sequences). Fault geometries and their development are ususally influenced by the structural and stratigraphic setting of the areas where they take place and these two seismic sequences, in particular, highlighted how pre-existing inherited discontinuities affected both faulth growth and seismogenic ruptures. Major factors controlling fault development and, consequently, the associated seismogenic behavior are (among others) (i) frictional behavior changes due to variations in the mechanical stratigraphy (from velocity weakening to velocity strengthening), (ii) variations of the fault geometry and (iii) occurrence of secondary and/or pre-existing faults. A good knowledge of these factors and of their influence can be of great help to improve the knowledge of active fault and in particular of their surface evidences that are often the only available data. For these reasons, in this research we carried out different sets of analog models to study the role of pre-existing, thin mechanical discontinuities on the development of new faults. For these models we used wet clay as the analog material and we reproduced both normal and reverse faults. Our results show that the upward propagation of the new faults is highly influenced by the presence of pre-existing discontinuities that, depending on their orientation, can accelerate or decelerate the rupture propagation. of the. The presence and the orientation of the mechanical discontinuities are also the factors promoting or inhibiting the formation of secondary structures (e.g. bending-moment faults) and affecting the shape of the fault-related syncline anticline pair
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.T13A2663S
- Keywords:
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- 8118 Dynamics and mechanics of faulting;
- TECTONOPHYSICSDE: 8120 Dynamics of lithosphere and mantle: general;
- TECTONOPHYSICSDE: 8159 Rheology: crust and lithosphere;
- TECTONOPHYSICSDE: 8163 Rheology and friction of fault zones;
- TECTONOPHYSICS