Improved seismic velocity reference model from local earthquake data in Northwestern Italy

Resolution and reliability estimates of results obtained by seismic tomography strongly depend on the reference model. Inadequate initial reference models may severely distort tomographic images or introduce artefacts that lead to misinterpretations of the results. Reference models are usually obtained by means of a priori near-surface geological information or by geophysical information derived by controlled-source seismology.
Starting from the idea that a reference model must approximate the weighted average of data selected for the three-dimensional (3D) inversion, one-dimensional (1D) model for Northwestern Italy is derived that is able to minimize mean of RMS of a set of well-locatable earthquakes, by computing a solution of the coupled hypocentre 1D velocity problem.
Such a model, termed the Minimum 1D model, can be used both as an initial reference model for 3D inversion and as a reference velocity model for high-quality routine earthquake location.