Constraining the strength of megathrusts from fault geometries and application to collision zones
Abstract
In the last two decades, geophysical and geodetic observations provided detailed insights into the physical properties of convergent plate margins and it is now well documented that megathrusts at subduction zones are exceptionally weak. In comparison, very little is known about the strength of megathrusts at collision zones, but they are often envisaged to be mechanically stronger than subduction megathrusts due to the poor dehydration potential of continental crust. Here we present a Coulomb wedge approach that allows to reliably constrain the strength of megathrusts by taking the geometry of wedge internal faults into account. We apply the approach to the European Alps and Himalayas and show that the collision megathrusts are similarly weak as subduction megathrust and that also the associated orogenic wedges are not significantly stronger. Using the example of the European Alps, we discuss how a weak megathrust may have caused a switch from contractional to extensional tectonics during the growth of the orogen.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFM.T23F0676D
- Keywords:
-
- 1242 Seismic cycle related deformations;
- GEODESY AND GRAVITY;
- 7215 Earthquake source observations;
- SEISMOLOGY;
- 8123 Dynamics: seismotectonics;
- TECTONOPHYSICS;
- 8180 Tomography;
- TECTONOPHYSICS