Cook Inlet DAS (CI-DAS): A Year-Long Experiment Studying Structure, Seismicity, Ocean Waves, and Acoustics Offshore Southern Alaska
Description:
Since June 8, 2023, a Sintela Onyx interrogator unit from the University of Washington FiberLab has recorded continuous DAS data across two 85-km spans of buried seafloor telecom fiber in Alaska’s Lower Cook Inlet: one span running NW from the city of Homer to Iliamna Bay, near Augustine Volcano, and the other running SW towards Kodiak Island. The DAS was deployed with a NAS for local data storage and both CPU and GPU servers, enabling real-time edge computing on the continuous data without file transfer. The DAS data is augmented by a land-based experiment, the Alaska Broadband Accessory Deployment for GEophysical Research (Alaska BADGER), which supplies 3C broadband data from the western Kenai Peninsula. Over the first 6.5 months, the DAS system recorded 2881 regional and local earthquakes, spanning a wide range of magnitudes (Ml 0.6 to Mww 7.2) and depths (~0 to 196 km). Our open-source edge compute software automates daily extraction of earthquake waveforms for USGS ANSS cataloged events and transfer of the event data to a server at the University of Washington. Daily reports are also automatically generated and pushed to researchers by email, summarizing recording statistics in order to monitor data quality. Work is ongoing to implement a machine-learning based phase picking and denoising workflow, for eventual use in source studies and travel-time tomography. We are also cross-correlating both ambient noise and earthquake coda waves to construct multi-modal Scholte wave dispersion curves along each cable and invert for the shallow velocity structure of Cook Inlet sediments. Results show an extremely soft sediment layer with a power-law shear-wave velocity profile overlying a stiff basement, the depth of which varies systematically across the inlet. We also record the quasi-static deformation of the seafloor from ocean surface gravity waves. By comparing DAS data with a CDIP wave buoy located ~500 m from the cable in 40 m water depth, we demonstrate that it is possible to measure common wave statistics, including mean wave period and significant wave height, using an empirical transfer function approach.
Session: Structure and Behavior of the Alaska-Aleutian Subduction Zone [Poster Session]
Type: Poster
Date: 5/3/2024
Presentation Time: 08:00 AM (local time)
Presenting Author: Ethan
Student Presenter: No
Invited Presentation:
Authors
Ethan Williams Presenting Author Corresponding Author efwillia@uw.edu University of Washington |
Shima Abadi abadi@uw.edu University of Washington |
Kasey Aderhold kasey.aderhold@earthscope.org EarthScope Consortium |
Paul Bodin bodin@uw.edu University of Washington |
Marine Denolle mdenolle@uw.edu University of Washington |
Veronica Gaete Elgueta velgueta@uw.edu University of Washington |
Eva Golos golos@wisc.edu University of Wisconsin-Madison |
Bradley Lipovsky bpl7@uw.edu University of Washington |
Yiyu Ni niyiyu@uw.edu University of Washington |
Qibin Shi qibins@uw.edu University of Washington, Seattle, Washington, United States |
William S D Wilcock wilcock@uw.edu University of Washington, Seattle, Washington, United States |
Cook Inlet DAS (CI-DAS): A Year-Long Experiment Studying Structure, Seismicity, Ocean Waves, and Acoustics Offshore Southern Alaska
Category
Structure and Behavior of the Alaska-Aleutian Subduction Zone