How do Local Earthquake Tomography and inverted dataset affect earthquake locations? The case study of High Agri Valley (Southern Italy)

Local earthquake tomography allows to both image the subsurface elastic properties of an area and to locate earthquakes. In this work, we discuss the choice of best parameterization in a tomographic model and the influence of retrieved velocity models on the accuracy of earthquake location in the High Agri Valley, southern Italy. The tomographic inversions were carried out with two datasets (dataset A and dataset B). Dataset B was obtained by integrating in the dataset A the data recorded by a very dense seismic network deployed around a specific cluster of seismicity. Velocity models obtained from the inversion of the two datasets are characterized by the same parameterization. However, the anomalies retrieved by the inversion of the second dataset look more reliable, based on results of checkerboard test. The retrieved 3D velocity model contributed to improve the accuracy of earthquake locations with respect to the 1D model. Data recorded by a very dense network in dataset B further contributed to reduce the errors and to improve the clustering of hypocentral positions of the best azimuthally covered cluster of seismicity. The importance of a 3D velocity model and of a proper network geometry for earthquake location is therefore demonstrated.