High frequency short microseisms events observed off the coast of Sicily

Microseisms, or seismic noise generated from the interactions of wind driven gravity waves, define a unique connection between the sea and solid Earth, with associated seismic surface waves dominating global ambient seismic noise records. The use of Distributed Acoustic Sensing (DAS) technology applied on fibre optic submarine cables provides a new exciting way for detailed characterisation of the offshore microseism wavefield. However, the use of such technology at its full potential calls for applications where continuous monitoring is key, raising further the questions regarding strategies for handling the generated data.

As part of the Geo-INQUIRE transnational access program, DAS data were collected at the INFN-LNS submarine fibre optic cable infrastructure offshore Catania over a period of 10 days in September 2025. The data were investigated to further characterize the offshore microseism signature in the Eastern Sicily region. Compared to more standard microseisms signatures usually observed on land stations that can last over a couple of days, here shorter events are observed. Over the recording period, those events appear to be consistently dominating different portions of the cable in the frequency range 0.5 to 2Hz. With a duration of less than ten hours on average, they are likely reflecting the rapid evolution of sea state conditions driven by the changing local winds.

During the OMAC (Optimizing DAS data selection for Microseisms Analysis offshore East Sicily) project, DAS acquisition workflows were also tested towards a more efficient handling of DAS data. For instance, over long acquisitions near real-time “cataloguing” of those microseisms events would reduce excessive storage of the raw data and generate a dataset ready for specific applications exploiting microseisms (seismic imaging, weather monitoring, …). A subset of data was also exported in miniseed format on the Italian EIDA node, to facilitate dissemination and virtual access to infrastructure’s data.

Geo-INQUIRE is funded by the European Commission under project number 101058518 within the HORIZON-INFRA-2021-SERV-01 call.