Testing Models of Active Extension (TMAX)

Plate tectonics shapes our world, influencing climate, biodiversity and resource distribution. The plate tectonic cycle starts with continental rifting: the process by which the Earth’s continental crust stretches, cracks, subsides and eventually breaks forming ocean basins and their margins. These margins, the locations of past active rifting, are the source of important mineral resources, sites of future CO2 and hydrogen storage and could become sites of geothermal energy production. Early-stage continental rifting establishes the structural template for these margins, controlling the distribution of sedimentary basins (for subsurface fluid storage) and the geometry of faults (sites of mineralisation and hot fluids). However, how fault geometry and crustal stretching evolve during the first few million years of continental rifting is one of the most poorly understood parts of plate tectonics. This is because ocean basin margins, although common and well-studied, do not preserve a record of the initial rift processes due to overprinting and masking over 10-100’s millions of years.
The only way to fill this “plate-tectonic-blind-spot” is by studying active rift zones, where the continental rifting process is in its infancy and happening today. These active rifts are also zones of intense seismicity and a significant hazard for local populations. The size and shape of faults controls the maximum earthquake size possible on a fault, so determining this information is vital for seismic hazard assessment.
The Corinth Rift in Greece is one of the most active rift systems on Earth today, and our knowledge of how the upper few km of the crust has stretched over the last 1-2 millions of years is not matched at any other rift. However, we are missing information on the processes acting in the crust at depths deeper than a few km along the entire rift, leading to important unanswered questions, such as: Are the dominant faults steep or shallow dipping? Does the geometry of faulting change along the rift and with time? Does the crust thin uniformly or variably along the rift and with depth?
We will answer these questions by using seismology to accurately record thousands of small earthquakes in the Corinth rift. Seismology is a powerful and sophisticated tool to solve tectonic problems facilitated by increasingly advanced artificial intelligence technology to aid small earthquake detection. We will install 35 seismometers around and in the Gulf of Corinth to accurately detect the earthquake activity of the rift. The locations of the earthquakes and the sound waves they generate that travel through the Earth can be used to resolve the thickness of the Earth’s crust to determine how it is deforming during rifting, and to work out which of the geological faults are most active and the geometries of these faults. This provides vital information for understanding rifting processes and mitigating earthquake hazards in this rift and other active rifts worldwide. Corinth is the only location where existing data combined with new seismicity data from our proposed project allow the nature of the first phase of rifting- the first phase of the plate tectonic cycle- to be fully recovered. Our new knowledge of how rifts start to form will be used to disentangle the geological record at the many, much older rifted continental margins on Earth, allowing rifts to reach their full potential as we make the transition to sustainable energy and resources.