Innovative Approaches to Fault Detection: Integrating Geophones and DAS in the Budoia-Aviano Thrust Case Study

This study evaluates the effectiveness of standard seismic reflection/refraction acquisition system and Distributed Acoustic Sensing (DAS) in detecting the buried segment of the Budoia-Aviano Thrust in northeastern Italy. It is conducted as part of the NASA4SHA PRIN Project, “Fault segmentation and seismotectonics of active thrust systems: the Northern Apennines and Southern Alps laboratories for new Seismic Hazard Assessments in northern Italy.”
Within the seismotectonic framework of the eastern Southern Alps the Budoia-Aviano Thrust accommodates regional compressional deformation in a low strain-rate setting (Poli et al., 2014; Patricelli et al., 2024). Many geological and morphotectonic evidence testify the recent activity of the Budoia-Aviano Thrust. Considering the significant historical seismicity of the area, understanding the fault’s geometry and kinematics is crucial for seismic hazard assessment and for advancing knowledge of active thrust systems and blind faults in the region.
To investigate the fault’s hidden geometry, four seismic lines were acquired: one in the Aviano and three in the Budoia  municipalities respectively. Seismic waves were generated using as source a seismic shotgun and recorded using two complementary methods. Geophones (4.5 Hz, 5m spacing) were selected for their deeper penetration capability, while DAS, with its 1m spatial sampling, provided higher-resolution imaging of shallow features. Both acquisition system were deployed under similar conditions to facilitate comparison and integration of the datasets.
Preliminary results reveal key insights into the subsurface structure. Seismic reflection data identify offset stratigraphic layering and discontinuities suggestive of potential fault traces, aligning with the expected thrust geometry. Seismic refraction delineates velocity variations corresponding to lithological contrasts and deformation zones, adding constraints on fault characterization. The DAS data, still under analysis, is expected to enhance imaging of subtle near-surface features, complementing the ‘geophones’ ability to image deeper structures.
The results highlight the complementary strengths of geophones and DAS: geophones excel at imaging deeper fault geometries critical for defining the thrust structure, while DAS captures detailed variations near the surface. The integrated datasets adopt a multi-scale geophysical approach, improving the resolution of the Budoia-Aviano Thrust’s buried segment.
This research provides valuable insights into the geometry and kinematics of active thrust systems in the eastern Southern Alps, contributing to improved seismic hazard assessments and informing future geophysical investigations in similar tectonic settings.