Overview of high resolution seismic prospecting in pre-Alpine and Alpine basins

Several high resolution seismic surveys were conducted in Alpine and pre-Alpine Lombardia (Northern Italy) valleys in order to reconstruct the geometries of the sediments filling the valleys, their seismo-stratigraphy and the rock basement depth. The acquisitions were made mainly in the framework of the CARG (Geological CARtography) project for the new geological map of Italy and under different research programs between the National Research Council and Regione Lombardia. The research firstly shows the capability of seismic methods in support of Quaternary research, and secondly demonstrates the response of different geomorphological features in particular: glacial valley, terminal moraine, deeply eroded valley and alluvial plain. Different tests were carried out in the seismic surveys in order to optimize the acquisition techniques for shallow prospecting (100-1000 m depth). The data were processed by applying a seismic refraction inversion technique, in addition to standard reflection processing. The integration of the two data sets improves the seismic migration of the reflection sections and the seismic interpretation, producing well-constrained seismo-stratigraphic sections coupled with an accurate seismic velocity section. The quality of the reflected events is generally higher in the glacial domain than in the fluvioglacial eroded valley, probably due to a stronger impedance contrast between soft sediments and hard rock. The terminal moraine sections show an intermediate quality of reflection record.