Multi-parameter seismic attenuation tomography of the Calabrian crust (Italy) using MuRAT3D

Abstract

Seismic attenuation, controlled by scattering and intrinsic absorption processes, represents a fundamental property for investigating crustal heterogeneity, fracturing, and fluid distribution. Here we present results from 3D attenuation tomography in the Calabrian Arc (Southern Italy), based on a relocated local-earthquake dataset analyzed within the MuRAT3D framework (De Siena et al. 2014). The study relies on a dedicated dataset of ~490 local earthquakes recorded between 2016 and 2024 by integrating local and national seismic networks. Event selection was designed to ensure homogeneous spatial and depth coverage while limiting clustering effects. P- and S-wave arrivals were manually picked, and earthquakes were relocated using a combined deterministic–probabilistic approach, producing a robust dataset optimized for attenuation analysis (Schweitzer, 2001; Chiappetta and La Rocca, 2024).

MuRAT3D enables a multi-parameter characterization of seismic energy loss by exploiting different portions of the seismic waveform. Scattering is investigated through Peak Delay (PD) derived from envelope broadening, while total and intrinsic attenuation are described by the quality factors Q and Qc. Analyses were carried out at discrete frequencies (1.5, 3, 6, 12, and 18 Hz), showing that only specific frequency bands yield stable and physically consistent attenuation parameters, reflecting the validity limits of the underlying assumptions and different seismic wave propagation regimes. The resulting 3D attenuation images display coherent, laterally variable patterns, with strong contrasts between continental and offshore domains and localized anomalies related to pronounced crustal heterogeneities and possible interactions with deep structures.Ongoing analyses aim to further refine attenuation patterns and their geological interpretation.