Long- and short-term deformation of convergent plate margins: Numerical modelling of seismic cycles at the South-Chilean oblique subduction zone

• Applicant: Dr. Béatrice Cailleau
• Subject Area: Palaeontology
• Term: from 2008 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 87364802

The subduction of the Nazca plate beneath the Southern Andes has resulted in several destructive historical earthquakes. These earthquakes appear to re-occur in cycles which, together with the oblique subduction direction, influence active deformation in the Chilean forearc and arc on different time scales. Although tectonic deformation is of high importance for hazard assessment, the relationship between the short-term and the long-term deformation of the upper plate is not well understood. The short-term deformation is related to transient elastic and viscous stresses that are released at earthquakes and the following decades. The long-term deformation, in contrast, is exhibited by permanent structures such as a strike-slip fault in the volcanic arc that accommodates northward migration of a forearc sliver, as well as basins and peninsulas in the forearc. This is a proposal to develop numerical models that incorporate self-running repeated earthquakes (seismic cycles) and the Theological heterogeneities of the plate margin with the goal to better understand the Andean crustal deformation on long- and short-term scales. We will investigate (a) the migration of the forearc and fault reactivation arising from oblique convergence, and (b) the addition and removal of material at the thrust interface that may be responsible for forearc basin and peninsula. These processes shall be combined and compared to GPS, gravimetric, seismic and geological data. The far-reaching goal of this study is to better identify the characteristics of the coupling at an oblique subduction thrust interface, and to test how the timing, size and location of earthquakes are linked to the short-term and the long-term crustal deformation.

• DFG Programme: Research Grants