Description
The benefit of distributed acoustic sensing (DAS) in monitoring natural hazard and environment phenomena is widely proven. Accurate monitoring requires, however, efficient spatial and temporal data sampling and acquisition. The latter depends on different parameters that must be adjusted to optimize the DAS survey design and quality. In this task we will define the acquisition parameters of the fiber-optic cable allowing reliable monitoring of natural hazards (i.e., earthquakes and tsunamis) and environment (currents, sea state, whales, soundscape, etc.). These will include the length of the fiber-optic to be interrogated, the optical power and pulse width, the interrogation pulse rate, the spatial sampling resolution, the gauge length and the deviation time. The preparation of such parameters will help optimizing the spatial and temporal sampling to ensure acquiring high-quality data for the monitored natural and environmental phenomena.
Analysis of the diverse phenomena to be investigated, seismic ground motion, infragravity waves as proxy to tsunami waves, sea state (wave height, wave period), surface currents, whale vocalizations, natural and anthropogenic soundscape requires a wide range of tools to be implemented, waveform displays, real-time spectrograms, f-k diagrams, phase dispersion diagrams, PSD in space and time, each tuned for its application. This task will provide the requirements for each tool and each envisaged application. Given that DAS generates an enormous amount of real-time data, the task will also make a proposal on the information to be transferred in real-time and on the location of the processing workload, in-situ or at the collecting center after transmission, and suggestions on the choice of real-time vs. deferred time, vs. on call processing.
The output of this task will contribute to the initial setting of both DAS recording to be done in task 2 and parameters processing and analysis to be developed in task 3.
Expected results
The primary goal of this task is to define the key acquisition parameters of the fiber-optic cable allowing reliable monitoring of natural hazards (earthquakes and tsunamis) and environment (currents, sea state, whales, soundscape, etc.). In the end a set of recording and processing parameters will be established so that the wide scope of signals from the ground and the ocean can be properly investigated.