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Abstract

Distributed Acoustic Sensing (DAS) is being explored in a variety of environments as a promising technology for the recording of seismic signals in dense array configurations. There is a particular interest for deploying DAS arrays on the ocean floor, as this environment presents formidable challenges for conventional seismology. Recent DAS studies on submarine cables demonstrate promising data fidelity showing detections of local and teleseismic events, as well as microseisms, infragravity waves and other oceanic signals spanning a broad frequency range. However, most of such experiments are short-term (lasting a few days to a few weeks) and lack systematic assessment of the instrument response, background noise and its seasonal variations, and, more generally, instrument capability. Here, we describe first results from a longer term (1 year starting in July 2022) DAS experiment on the Monterey Bay Accelerated Research System (MARS) cable in Monterey Bay (California), which extends offshore for a length of 52 km, and on which we have been acquiring data since July 2022, for almost a year. Here we describe the experiment and present examples of observations background noise and a variety of detected signals, including microseisms, infragravity waves, regional and teleseismic earthquakes (in particular T-waves) over the first 10 months of the deployment. In addition to these observations, one of our goals is to integrate the continuous DAS data into the real-time seismic monitoring system in northern California including Earthquake Early Warning.