ZIP – Zooming in between plates: GFZ

ZIP – Zooming in between plates: A european Initial Training Network

Half of the world's population lives on top or nearby subduction zones, in coastal areas repeatedly devastated by large earthquakes, tsunamis or volcanic eruptions. Giant earthquakes occurring on subduction zone mega-thrusts took about 250 000 lives, the most devastating being the 2004 Mw 9.2 Aceh earthquake in Sumatra, and the recent Mw 9 2011 Tohoku earthquake in Japan (with World Bank cost estimates > 200 billion € for the latter). The ZIP Network (Zooming In between Plates) unites 8 European organizations (UPMC, GFZ, ETH, INSU, CSIC, etc., and a number of industry partners aiming to (1) determine the dimensions, geometry and physical properties of the plate interface, (2) model time-integrated material fluxes, (3) understand how rock rheologies relate to seismicity, megathrust earthquakes and control earthquake nucleation and rupture propagation.

The contribution of GFZ, section 4.1 focusses on imaging and characterizing deformation patterns at plate interfaces. We plan to image the deformation patterns at the plate interface, characterize its relationship to rheological parameters (using state-of-the-art seismological and geodetic data from well-monitored margins: e.g. Chile, Japan), and combine these observations with field-based studies on the fluid-assisted processes in rocks via upscaling and kinematic modeling of processes driving the various deformation types along the plate-boundary. The methods employed include GPS, InSAR, seismic tomography and fieldwork. The data will constrain numerical models of fault slip, pore elastic deformation, viscous response and thermo-mechanical processes.

Conceptual diagram of fluid sources and transport in the plate interface region. Hydrothermally-altered rocks from the Mocha Fracture Zone dehydrate during subduction, and expelled fluids migrate upwards along the fractures into the plate interface region where they are trapped due to relatively low permeabilities of the upper plate. North of the Mocha Fracture Zone the oceanic plate is less fractured17,20. Consequently, lesser initial water content leads to lower pore fluid pressures as seen from the marked anticorrelation between Poisson’s ratio and locking degree. White stars represent the location of seismic events.

Further information

Further information are available on the project webpage www.zip-itn.eu or by contacting ZIP-Supervisor for GFZ Prof. Dr. Onno Oncken.

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