GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 3.3 ______ ___ GNGTS 2023 Distributed Acoustic Sensing (DAS) data for seismic monitoring: influence of cable geometry and installation context E. Bozzi 1 , N. Piana Agostinetti 1 , G. Saccorotti 2 , A. F. Baird 3 , C. Becerril 4 , B. Biondi 5 , A. Fichtner 6 , S. Klaasen 6 , N. Lindsey 7 , T. Nishimura 8 , J. Shen 9 , A. Ugalde 10 , F. Walter 11 , S. Yuan 5 , T. Zhu 9 1 University of Milano-Bicocca, Milano, Italy. 2 Istituto Nazionale di Geofisica e Vulcanologia (INGV), Pisa, Italy. 3 NORSAR, Kjeller, Norway 4 Université Côte d'Azur, CNRS, Observatoire de la Côte d'Azur, IRD, Géoazur, Valbonne, France 5 Stanford University, Stanford, California, USA 6 ETH Zürich, Zürich, Switzerland 7 FiberSense TM 8 Tohoku University, Tohoku, Japan 9 PennState University, State College, Pennsylvania, USA 10 Barcelona Center for Subsurface Imaging, Barcelona, Spain 11 Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Uitikon, Switzerland Introduction Distributed Acoustic Sensing (DAS) technology exploits laser interrogation of fiber optic cables (FOCs) to retrieve a very-densearray of longitudinal strain/strain-rate sensors (Zhan, 2020). DAS detects phase changes in the backscattered energy from natural fiber inhomogeneities. Raw optical measurements are integrated along a discrete cable portion, called “gauge length” and then related to local strain/strain-rate at each “DAS channel”. DAS can record external inputs deforming FOCs in a broadband frequency range (Paitz et al., 2021), with a maximum interrogation range around 100 km (Landrø et al., 2021). DAS is a promising research field for seismology. Indeed, it allows for unprecedented wavefield spatial sampling (up to < 1 m) and potential ubiquitous monitoring, especially when pre-existing telecommunication optical fibers are interrogated (Lindsey & Martin, 2021). As a matter of fact, it can map subsurface heterogeneities (Jousset et al., 2018; Lindsey et al., 2020; Lior et al., 2022, Yuan et al., 2020), monitor natural (Lindsey et al., 2017; Biondi et al., 2017; Ugalde et al., 2022) or induced seismicity (Karrenbach et al., 2019) , especially in geothermal fields (Lellouch et al., 2020; Obermann et al., 2018), implement fast response to study aftershock sequences (Li et al., 2021), characterize natural seismicity induced by glacier movements (Walter et al., 2020) and urban noise (Biondi et al., 2022; Shen and Zhu, 2021). However, DAS data is usually affected by lower