[S-TT41] Seismic monitoring and processing system

[STT41-P03] An example analysis of high precision Geophysical observations with Hilbert-Huang Transform

*Makoto OKUBO^1,5, Hirotaka Takahashi⁵, Akito Araya³, Satoshi Itaba², Masaki Kanao⁴ (1.Natural Science Cluster, Kochi University, 2.National Institute of Advanced Industrial Science and Technology, 3.Earthquake Research Institute, University of Tokyo, 4.National Institute of Polar Research, 5.Tokyo City University)

Keywords:Hilbert-Huang Transform, Geophysical observations, ultra wideband/high precision

High-precision geophysical observations are necessary to observe minute variations occurring in the Earth's deep interior. In many cases, only very long-period fluctuations are observable because short-period fluctuations are attenuated during the propagation from deep to the earth's surface. Therefore, the instruments are required to have ultra-wide bandwidth and high accuracy. In recent years, instruments capable of such ultra-broadband and high-precision observations have become available. ROIS-DS joint project [015RP2021, 018RP2022] has enabled us to start trying to develop a method to detect interested deep phenomena from the ultra-wide bandwidth observation recordings.
We try to apply a signal extraction method based on the Hilbert-Huang transform (HHT) combined with strain analysis. We present here a laser extensometer with 1500 m baseline length 10^-13 accuracy (e.g., Araya, 2017), a multi-component borehole strainmeter (e.g., Okubo et al., 2005 and Itaba et al., 2018), and a superconducting gravimeter (Yokoyama et al., 2017) as an example of high S/N.

Acknowledgement:
We would like to express their gratitude to the following organizations for their support: ROIS-DS joint [No. 015RP2021, 018RP2022] supports to conduct this research. The crustal deformation database operated by Hokkaido University was used to obtain the gravimetric data.