RAPID: Multiplexed Distributed Acoustic Sensing (DAS) at the Ocean Observatory Initiative (OOI) Regional Cabled Array (RCA)
In May 2024, a team of scientists led by Dr. Brad Lipovsky at the University of Washington conducted a test of multiplexed distributed acoustic sensing (DAS) along the more southerly of two submarine cables of the OOI Regional Cabled Array (RCA) extending off Pacific City, Oregon. DAS uses backscattered light to measure fiber strain with spatial resolution of meters and at frequencies typically recorded by seismometers. Whereas previous DAS experiments on the RCA sought to demonstrate the use of DAS on OOI RCA infrastructure during a time period when the RCA cables were not being used for communication with the RCA instruments, the May 2024 study sought to demonstrate the use of DAS during a time when active communications were taking place on the same optical fiber as the DAS observations.
The 4-day test was conducted from May 6-10 during a scheduled maintenance shutdown of the OOI RCA. The OOI RCA has two cables extending off Pacific City Oregon, the north cable which extends to Axial Seamount and the south cable that loops back onto the continental margin off Newport to the south of Pacific City. Each cable has two optical fibers, the transmit and receive fibers for observatory data. The multiplexed DAS observations extended to the first optical repeater on the South cable which is located at about 95 km offshore.
The experiment used an Alcatel Subsea Networks (ASN) optoDAS interrogator. From 2024-05-06 15:57:34 to 2024-05-10 14:50:35 UTC, we acquired continuous DAS data on the South cable of the OOI RCA (Figure 1). At 15:00 UTC on May 6 the network was disconnected and we connected the interrogator to the fiber at the outermost module of the submarine terminal system using an in-line C/L filter. Our team tested DAS acquisition parameters for approximately one hour before continuous recording commenced. Around 19:00 UTC on May 7, the network was reconnected to the RCA South cable, through the C/L filter, and the OOI team resumed data telemetry while DAS data acquisition continued. Shortly before 15:00 UTC on May 10, DAS data acquisition was stopped. The C/L filter was then removed, which required briefly disconnecting and reconnecting the RCA South fiber.
The data from the experiment are available by FTP. A description of the dataset is provided via Github repository, including a jupyter notebook that shows how to use the data.. Users may also sign up for a mailing list that will be used to share occasional updates. Note that the total volume of data is about 4 TB. Investigators may contact Mitch Elend to arrange to send hard disk drives which will be returned with the requested data.
Access DAS Data