Centroid Moment Tensor catalog with 3D lithospheric wavespeed model: the
2016-2017 Central Apennines sequence
Moment tensor inversions of broadband velocity data are usually managed
by adopting Green’s functions for 1D layered seismic wavespeed models.
This assumption can impact on source parameter estimates in regions with
complex 3D heterogeneous structures and rock properties discontinuities.
In this work, we present a new Centroid Moment Tensor (CMT) Catalog for
the Amatrice–Visso–Norcia (AVN) seismic sequence based on a recently
generated 3D wavespeed model for the Italian lithosphere. Forward
synthetic seismograms and Fréchet derivatives for CMT–3D inversions of
159 earthquakes with Mw ≥ 3.0 are simulated using a spectral–element
method (SEM) code. By comparing the retrieved solutions with those from
Time Domain Moment Tensor (TDMT) catalog, obtained with a 1D wavespeed
model calibrated for Central Apennines (Italy), we observe a remarkable
degree of consistency in terms of source geometry, kinematics, and
magnitude. Significant differences are found in centroid depths, which
are more accurately estimated using the 3D model. Finally, we present a
newly designed parameter, τ, to better quantify and compare
a–posteriori the reliability of the obtained MT solutions. This
parameter measures the goodness of fit between observed and synthetic
seismograms accounting for differences in amplitude and arrival time,
percentage of fitted seconds, together with the usual L2–norm estimate.
These CMT–3D solutions represent the first Italian CMT catalog based on
a full–waveform 3D wavespeed model and provide robust source parameters
with potential implications for the structures activated during the
sequence. The developed approach can be readily applied to more complex
Italian regions where a 1D wavespeed model is underperforming.