EGU25-17308, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-17308
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
Advanced Imaging of a Magnitude 6 Earthquake Using Extended Ocean Bottom DAS Data off-shore Chile.
Yuqing Xie, Jean-Paul Ampuero, Martijn van den Ende, Alister Trabattoni, Marie Baillet, and Diane Rivet
Yuqing Xie et al.
  • University of Côte d'Azur, GéoAzur, Sophia-Antipolis, France

Utilizing Distributed Acoustic Sensing (DAS) data recorded along three segments of an ocean bottom cable off the coast of Chile (~450 km in total), we have imaged the rupture process of an intermediate-depth earthquake of magnitude 6 , which occurred in Argentina on September 21, 2014. This earthquake is located approximately 400 km away from the cable. This marks a significant advancement in seismic monitoring: our approach fully exploits the high-density and wide-aperture capabilities of ocean bottom cables to provide low-cost, high-resolution observations of earthquake rupture processes across extensive geographic areas.

Our methodology integrates several key procedures to effectively address the challenges of imaging distant, moderate-size seismic events in environments with complex velocity structures using array techniques. The conversion from strain rate to velocity helps suppress scattering from sediment layers. Array processing based on cross-correlations between the mainshock and an empirical Green’s function (an aftershock) addresses the interference effect of multiple seismic phases, enhancing the coherence of waveforms along the entire cable length at high frequencies (1 to 4 Hz), and enabling a spatial resolution of approximately 1 km in the north-south direction. We further align the resultant data to correct travel time errors effectively, thereby improving the accuracy of our location estimates. Additionally, we average the results of 20 independently sampled subsets from the dense DAS sensors, significantly sharpening the imaging resolution and enhancing accuracy.

With these techniques, our analysis reveals three strong high-frequency radiation sub-sources, indicating a rupture propagation of 8 km over 6 seconds. These findings provide insights into the rupture directivity and nodal plane orientations, potentially indicating the mechanisms of strain localization on normal faults within the seismic slab at a depth of ~ 130 km. This application opens new pathways for further research in seismic monitoring and earthquake kinematics in previously unreachable oceanic environments. It also has the potential to accumulate a rich database of the kinematics of smaller, more frequent earthquakes, which require exceptionally high-resolution observations previously unattainable.

How to cite: Xie, Y., Ampuero, J.-P., van den Ende, M., Trabattoni, A., Baillet, M., and Rivet, D.: Advanced Imaging of a Magnitude 6 Earthquake Using Extended Ocean Bottom DAS Data off-shore Chile., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17308, https://doi.org/10.5194/egusphere-egu25-17308, 2025.