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

[STT42-P06] Development of a Ground Monitoring Method Using Optical Fiber DAS and Microtremor Survey

*Hiroyuki Fujiwara¹, Hiromitsu Nakamura¹, Takashi Kunugi¹, Shohei Naito¹, Shigeki Senna¹, Masato Sato¹, Ken Sakurai², Chisato Konishi², Haruhiko Suzuki², Masaki Takebe³ (1.National Research Institute for Earth Science and Disaster Resilience, 2.OYO Corporation, 3.Mitsubishi Electric Software Corporation)

Keywords:optical fiber, Distributed Acoustic Sensing, microtremor survey, ground

In order to develop a ground risk assessment method for sedimentary plains where large cities are located, we have started to develop a basic fundamental technology for high density, high precision, wide area detailed ground monitoring by integrating DAS (Distributed Acoustic Sensing) using optical fibers as sensors and microtremor surveys. Using existing optical fibers and seismic observation facilities, we are developing ground monitoring techniques using optical fiber DAS, establishing long-term continuous monitoring techniques, and developing analytical methods integrated with microtremor surveys and seismic wave interferometry.
NIED has developed various seismic observation networks, including K-NET, and has conducted microtremor surveys in specific areas, such as the Kanto region, to improve the accuracy of the 250m-mesh ground model. However, in some cases, amplification characteristics are underestimated and seismic motions are estimated to be small, so we have not adequately modeled the three-dimensional heterogeneous structure of the actual ground.
We will present an overview of the research project aimed at establishing fundamental techniques for high-density, high-precision, wide-area, detailed ground monitoring by combining optical fiber DAS and microtremor survey, and a comparison of ground vibration measurement performance using multiple types of optical fiber cables and interrogators in the test field.