Seismicity along the northwestern edge of the Adria microplate
Abstract
This contribution is an overview of the seismic activity observed along the northwestern edge of the Adria microplate over the last 15 years. The study area stretches from Lyons to Turin, and from Geneva to Nice. The discussion focuses on several key zones where significant earthquakes occurred during this period, or where the connection between seismicity and tectonics provides clear-cut results. Our main conclusions are: E-W to NW-SE compression in the Ligurian Sea and at depth beneath the southwestern Po plain; in the core of the western Alps, widespread extension radial to the chain, with a component of right-lateral strike slip along faults longitudinal to the chain; in the European foreland, almost exclusively strike slip, either right-lateral along faults longitudinal to the chain or left-lateral in a conjugate direction. The observed right-lateral strike slip is consistent with an anticlockwise rotation of Adria about a pole in the Po plain, but the extension observed in the root zone cannot be explained with a simple rigid-plate model. This extension probably also involves gravitational collapse and/or slab roll-back or break-off.