Observing seismic and silent faulting related to a megathrust earthquake cycle: Joint application of InSAR and creepmeter ground displacement measurements

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Convergent plate boundaries at continental margins belong to the tectonically most active areas on earth and are the potential source of devastating earthquakes and tsunamis. While the bulk of strain accumulation occurs along the subduction interface, significant hazardous deformation occurs by fault activity in the overriding crust. Despite abundant evidence for surface faulting in northern Chile, it is largely unknown how upper plate faulting is related to stages of the subduction earthquake cycle. In the region between the cities Antofagasta and Arica, we propose to study the displacement rates and deformation mechanisms and surface response of the upper plate before, during and after large earthquakes. Past states of deformation will be studied by means of tectonic geomorphology in the field. The core of the project is then to study the ongoing state of deformation, for which we will apply methods of remote sensing and direct field measurements. Using satellite radar interferometry (InSAR) we attempt to detect ground displacements at faults at a resolution of centimetres. For an even more precise signal analysis we propose to use creepmeters at selected fault locations in order to resolve magnitude and temporal variability of fault slip at the submillimeter scale. The combination of these methods shall allow to investigate present fault displacement rates at various scales and to compare with the long term seismic cycle. Ultimately we want to develop an integrated model for episodic and permanent strain accumulation in the Chilean Forearc.