What is controlling plate motions over the minutes to decades timescale?

ongoing

Tectonic ground observations from Global Navigation Satellite Systems (GNSS) increasingly show that plate motions are non-steady. In some instances, these non-steady motions have been suspected as precursory motions to large earthquakes. However, the full spectral behaviour of transient plate motions, across minutes to decades, and kilometres to continental distances, is not well understood. Here, I propose a multi-pronged approach to study how faults and plates worldwide are moving in response to the geodynamical (interior) and geophysical fluid loading/tidal (exterior) boundary conditions. The major questions to address are: How transient is tectonic deformation over the minutes to decades timescale? What are the physical processes controlling the transient plate motions? To what extent are transient plate motions indicative of earthquake imminence? We will reveal the extent of non-linear tectonic motions by developing GNSS processing algorithms and applying these to data from the thousands of tectonic GNSS stations worldwide. With machine learning, numerical modelling, and laboratory experimentation, we will determine to what extent faults are modulated by variable regional tectonics and loading. We will develop kinematic and laboratory modelling strategies to better understand transient tectonic boundary conditions such as transient slab-pull at subduction zones. While analysis will span continental and global scales, we will also investigate the kinematics of faults and fault networks with dense GNSS observations at a higher resolution, using GNSS and seismic data from north-central Chile as well as from laboratory-scale analog modelling to track fault failure in unprecedented detail. In Greece, a world-class example of a seismically hazardous zone of fault-network complexity, we will set up a world’s first low-cost tectonic GNSS network to understand how microplate motions interact with the larger wavelength tectonic boundary conditions of the region.