Insar Role in the Study of Earth's Surface and Synergic Use with Other Geodetic Data: the 2014 South Napa Earthquake

This work focuses on the role of SAR Interferometry (InSAR) in the study of many phenomena characterizing the Earth's surface. We propose an advanced integration method in order to merge the InSAR data with other geodetic data, i.e. Multiple Aperture Interferometry (MAI), Pixel Offset Tracking (POT) and Global Positioning System (GPS). We apply the method to constrain the full 3D displacement field produced by the Mw 6.1 2014 South Napa Valley earthquake and then we used the results from the integration to perform the source modeling. The first Chapter is meant to introduce the topic of the progressive use of Remote Sensing geodetic data to support the activities of monitoring and hazard mitigation related to natural phenomena. Chapter 2 shows the application of the InSAR technique to reconstruct and model surface displacement fields induced by several phenomena. In Chapter 3, the 3D coseismic displacement map due to the 2014 Mw 6.1 South Napa earthquake, close the San Andreas Fault system (California), is estimated by using a method to merge InSAR and GPS data. InSAR data are provided by the latest satellite of the European Space Agency (ESA), i.e. Sentinel-1, whereas the GPS data were obtained from the BARD network and several online archives. In Chapter 4 we propose an improved algorithm for the data integration and test it on the Napa earthquake. Geodetic data from MAI and POT are added in the processing chain and the GPS data interpolation is modified according to the specific phenomenon. Futhermore, the source modeling is performed by inversion of the obtained 3D displacement component. The best fit is obtained by simulating a fracture in the fault segment in agreement with previous works. Finally, in the last chapter we discuss about the advantages and disadvantages of the data integration and the future perspectives.