Abstract. Improving the knowledge of seismogenic faults requires the integration of
geological, seismological, and geophysical information. Among several
analyses, the definition of earthquake focal mechanisms plays an essential
role in providing information about the geometry of individual faults and
the stress regime acting in a region. Fault plane solutions can be retrieved
by several techniques operating in specific magnitude ranges, both in the
time and frequency domain and using different data. For earthquakes of low magnitude, the limited number of available data and
their uncertainties can compromise the stability of fault plane solutions.
In this work, we propose a useful methodology to evaluate how well a seismic
network, used to monitor natural and/or induced micro-seismicity, estimates
focal mechanisms as a function of magnitude, location, and kinematics of
seismic source and consequently their reliability in defining seismotectonic
models. To study the consistency of focal mechanism solutions, we use a
Bayesian approach that jointly inverts the P/S long-period spectral-level
ratios and the P polarities to infer the fault plane solutions. We applied
this methodology, by computing synthetic data, to the local seismic network
operating in the Campania–Lucania Apennines (southern Italy) aimed to
monitor the complex normal fault system activated during the Ms 6.9, 1980
earthquake. We demonstrate that the method we propose is effective and can
be adapted for other case studies with a double purpose. It can be a valid
tool to design or to test the performance of local seismic networks, and more
generally it can be used to assign an absolute uncertainty to focal
mechanism solutions fundamental for seismotectonic studies.