[S-TT42] Applying optic fiber sensing to earth science

[STT42-P02] Comparing observed and synthetic DAS records of intra-slab earthquakes

*Suguru Yabe¹, Saeko Kita², Satoshi Ide³ (1.National Institute of Advanced Industrial Science and Technology, 2.Building Research Institute, 3.University of Tokyo)

Keywords:DAS, Intra-slab earthquakes, strain

“Distributed Acoustic Sensing” (DAS), which enables super dense seismic observation using fiber optic cable, has been focused recently because of its usefulness in seismic observations. We conducted DAS observation using fiber optic cables along Route 33 from Matsuyama to Kochi, which is settled for road maintenance, with the permission of Shikoku Regional Development Bureau. We settled DAS system of APSensing at the building in Matsuyama City and conducted DAS observation for about 10 days from February to March 2022 along ~50 km from the recorder to around prefectural boarders between Ehime and Kochi prefectures. Although the observation point is close to slow earthquake sources, no active slow earthquakes were observed nearby. On the other hand, several ordinary earthquakes, including two M ~3.5 earthquakes, were successfully recorded. We also conducted tap test to relate optic length along the fiber to geographic coordinates. In this study, we investigate DAS records of ordinary earthquakes by comparing them with synthetic ones. We used two moderate earthquakes listed in the F-net moment tensor catalog. Synthetic waveforms were calculated with strain waveform outputs of OpenSWPC (Maeda et al., 2017). We will report results on consistency between observed and synthetic waveforms and influences of seismic sources and structures on synthetic waveforms.

Reference
Maeda, T., S. Takemura, and T. Furumura (2017), OpenSWPC: An open-source integrated parallel simulation code for modeling seismic wave propagation in 3D heterogeneous viscoelastic media, Earth Planets Space, 69, 102, doi:10.1186/s40623-017-0687-2.