Detection of Earthquake Infragravity and Tsunami Waves With Underwater Distributed Acoustic Sensing

Underwater Distributed Acoustic Sensing (DAS) utilizes optical fiber as a continuous sensor array. It enables high-resolution data collection over long distances and holds promise to enhance tsunami early warning capabilities. This research focuses on detecting infragravity and tsunami waves associated with earthquakes and understanding their origin and dispersion characteristics through frequency-wavenumber domain transformations and beamforming techniques. We propose a velocity correction method based on adjusting the apparent channel spacing according to water depth to overcome the challenge of detecting long-wavelength and long-period tsunami signals. Experimental results demonstrate the successful retrieval of infragravity and tsunami waves using a subsea optical fiber in offshore Oregon. These findings underscore the potential of DAS technology to complement existing infragravity waves detection systems, enhance preparedness, and improve response efforts in coastal communities. Further research and development in this field are crucial to fully utilize the capabilities of DAS for enhanced tsunami monitoring and warning systems. Subsea Distributed Acoustic Sensing (DAS) uses optical fiber as an extensive sensor array for strain data collection over long distances. This study investigates its potential to augment infragravity waves warning systems by focusing on detecting infragravity waves and tsunamis induced by earthquakes. We developed a methodology that accounts for irregular sensor depths to enhance the detection of long-wavelength tsunamis. Our experimental validation demonstrates the successful detection of these waves through a subsea optical fiber. Therefore, this technology holds promise for fortifying existing infragravity waves warning systems and improving coastal preparedness. We try to use subsea Distributed Acoustic Sensing (DAS) to improve early warning systems for infragravity and tsunami wavesThe research focuses on detecting infragravity and tsunami waves triggered by earthquakesWe have developed a method to detect long-wavelength tsunami signals by adjusting sensor spacing according to water depth