Optimizing Passive Seismic Data Processing in Volcanic Areas with Irregular Source-Receiver Distributions

Understanding the complex subsurface structures in volcanic regions is crucial for effective hazard assessment and resource management. In such areas, traditional active seismic studies often require substantial human and material resources, while operating in densely populated areas. In the contrary, passive seismic data offers a valuable alternative by making use of the extensive seismic records accumulated over time, but introduces complexities such as unknown source location, magnitude and fault mechanism. This study aims to develop a workflow for processing passive-source seismic data with irregular source-receiver distributions, identifying reflection/converted phases to produce a seismic profile suitable for seismic reflection imaging. To achieve this, we simulated the Campi Flegrei caldera case-study with 400 micro-earthquakes, randomly distributed between 1 and 3 km in depth, and recorded by 13 stations. We explore different gather configurations and evaluate their effectiveness for seismic imaging. We apply several preprocessing steps to both synthetic and real seismic data to ensure high-quality imaging results. Reflection phases are carefully identified by utilizing the predicted theoretical arrival times of both reflected and converted phases. Finally, through this processing procedure, we ultimately generate a passive-source seismic profile with irregular source-receiver distributions, that is exploitable for Kirchoff migration imaging.