GEOPSY-DAS: An Interactive Plugin for Fast Visualization and Integration of Distributed Acoustic Sensing (DAS) in Ambient Vibration Processing

Since its release in 2005, the open-source Geopsy software has become a well-established tool for analyzing ambient vibrations and characterizing seismic sites through its user-friendly and efficient graphical interface. Although it was originally designed for standard sensors such as geophones and nodal arrays, Geopsy is evolving to keep pace with the increasing popularity of Distributed Acoustic Sensing (DAS).

We introduces a new Geopsy plugin specifically designed to handle the large, high-density datasets produced by fiber optic sensing. Our aim is to provide Geopsy users with a Graphical User Interface that is free from heavy coding requirements and allows seismologists to easily visualize and process massive DAS data streams, specifically while on the field. Users can quickly scroll through thousands of channels and multiple files simultaneously, enabling immediate quality control and preliminary analysis right after acquisition. It eliminates complex and heavy scripting to handle DAS datasets while maintaining high compatibility with existing Geopsy processing tools.

Geopsy-DAS includes an intuitive Geo-referencing module to easily map DAS channels to physical coordinates using sparse reference points. Specific features, such as tap tests, fiber symmetries or traffic can be pinpointed directly from the graphical trace display and Geo-referenced to refine the fiber path geometry. Once the channels have been set, the data can be easily processed with usual Geospy modules (filters, spectrograms, correlations, H/V, F-K, MASW, etc.) and take advantage of Geopsy powerful low-level processing capabilities. The plug-in also offers intuitive channel selection, enabling specific signal features to be tracked and extracted from large datasets across multiple files for a dedicated processing.

We demonstrate Geopsy-DAS in an experiment conducted in Grenoble, France, involving 12 km of 'dark fiber' running under a tramway line and across the city. Despite having almost no prior knowledge of the cable's path or the quality of its coupling, we successfully mapped its geometry. We identified and monitored various urban structures along the fiber, including several bridges, and captured their vibration response (damping, spatial coherence, etc.). It demonstrates the efficiency of the Geopsy GUI in handling DAS data for monitoring structural integrity and site characterization in noisy, complex environments, while maintaining high computing performance and a user-friendly interface.