Deploying the First Regional DAS Seismic Network in a High-Hazard European Region: the Case of Northeastern Italy

Abstract Distributed acoustic sensing (DAS) is rapidly emerging as a powerful complement to conventional seismic monitoring, enabling dense spatial sampling over tens of kilometers using existing fiber-optic telecommunication infrastructures. In this study, we present the design, implementation, and initial performance of a regional-scale DAS seismic monitoring network integrated within the operational framework of the Seismological Research Center of OGS in north-eastern Italy. The system is built upon dark fiber segments of a public telecommunication network and interrogated by multiple DAS units, covering several hundred kilometers of optical fiber and producing tens of thousands of virtual sensing channels. We describe the end-to-end workflow developed to support continuous DAS acquisition in an operational environment, including data conversion from proprietary formats to standard seismological archives, channel aggregation strategies, metadata handling, and real-time streaming through SeedLink and International Federation of Digital Seismograph Networks services. Attention is given to practical constraints related to data volume, latency, channel naming, and integration with existing seismic monitoring infrastructures. Using representative examples, we illustrate the capability of the network to record teleseismic and local seismic signals, to characterize spatially variable seismic noise conditions along fiber routes, and to contribute to earthquake location when combined with conventional seismic stations. These case studies highlight both the opportunities and current limitations of distributed acoustic sensing (DAS) for regional seismic monitoring, including issues related to channel localization, directional sensitivity, and effective sensing range. The presented network represents one of the most extensive operational DAS deployments for seismic monitoring in Europe to date. Our results demonstrate the feasibility of integrating large-scale DAS systems into routine monitoring activities and provide a reference framework for future developments toward multisensor, fiber-optic-based seismic observatories.