Prospección geofísica de la Falla de Sencelles (Mallorca, España): una metodología preliminar para la realización de trincheras de falla

Abstract

A detailed geophysical survey has been performed at the westernmost sector of the Sencelles Fault (Mallorca, Spain). This is devoted to near-surface data acquisition for a further realistic project of fault trenching in order to investigate fault activation during the 1851 Palma earthquake (MSK VIII). The investigated fault sector; near Sta. Eugenia, was selected after a detailed fieldsurvey of the entire fault zone. The sets of used geophysical techniques are seismic refraction, elogs, and VLF and e-dipolar ditches, with a total amount of five profiles for each one over an area of 200x400m along the selected fault sector. The numerical geophysical data has been inserted in a detailed topographic map at 0.5m levelling resolution, which will be used to perform high-resolution 3D digital models of both, the terrain and the fault zone at depth. Preliminary results indicate that there are, at least, 5m of recent sedimentary filling adjacent to the fault scarp, and that some kind of near-surface diapiric processes are likely to occur at the surveyed sector, complicating the expected simple fault geometry.