Azores Crustal Structure Derived From Receiver Functions

During the last two decades efforts have been put together to understand the processes responsible for the Azores plateau formation. The geodynamics of this plateau, located at the triple junction between America, Africa and European plates, is dominated by the tectonics of the triple junction and by hotspot activity. But, the relationship between islands volcanism and a possible plume beneath the Azores is still not well understood and the triple junction exact location is also under debate. From October 2000 to September 2002, temporary broadband seismic stations have been deployed in the Azores archipelago in the framework of the COSEA Memoradum of Understanding. These broadband data have been used to compute receiver functions and estimate the crustal structure beneath the islands. Radial receiver functions where analyzed by both inverse and forward modeling in order to obtain 1-D S-wave profile. Crustal receiver functions exhibit local effects and the stations can be separated into 2 groups. Flores and Corvo islands, that are located at the west of the ridge axis and central islands (Faial and Pico) display slow crustal S-wave velocity whereas the eastern island of Santa Maria is associated with fast crustal S-wave velocity. These results will be discussed in the Azores geodynamic context.