InSAR full-resolution analysis of the 2017-2018 M > 6 earthquakes in Mexico

The present study analyzes the sequence of 4 important earthquakes occurred in Mexico from September 2017 to February 2018, exploiting the large availability of InSAR data and analytical models, with a twofold goal: to privede new solutions for seismogenic sources, completely independent from seismological data, and to discuss methodological aspects related to the non-linear and linear inverse problem. We review and update an earlier study, focused on the concept of resolution, showing the level of detail achievable in the investigation of the slip distribution based on geodetic observations, according to data availability, fault locations and event magnitudes. We further give new insights into the relationship between fault resolution and parameter uncertainty, demonstrating that a realistic assessment is strictly related to a proper fault subdivision. We eventually discourage the use of qualitative approaches, such as the checkerboard test, to evaluate the data resolving power and suggest the adoption of quantitative indicators, like the Dirichlet Spread Function, normalized, easy to calculate and mathematically robust.