Stress tensor determination in France and neighbouring regions

摘要: Abstract The tectonic behaviour of different seismic regions France is inferred from the properties local stress tensor obtained focal mechanisms regional earthquakes. Polarities P-wave arrivals for several earthquakes are used in inversion and individual mechanisms. principal axes shape closely related to forces which generate ruptures on pre-existing faults. We analyse 142 magnitude above 3.7 occurred between 1965 1989. Good results some regions. northern Alps southern end Upper Rhinegraben show a quasi-compressive, strike-slip regime, with maximum stress-axis oriented NW-SE. regime changes an extensional type Rhenish Massif Lower Rhinegraben, direction minimum being NNE-SSW. central western (Central Armorican Massifs) exhibit combined faulting. strikes NE-SW direction. A strongly non-homogeneous field seems be present southwestern Alps, no unique could that region. This problem likely rapid variation space expected, given arc-like geometry mountain range. Pyrenean domain unresolved due lack data and, moreover, existing globaly inconsistent. Nevertheless, those well constrained suggest NNW-SSE NW-SE part Pyrenees. Thus, fairly homogeneous at scale most territory except highly deformed belts.