[S-TT51] 地震観測・処理システム

[STT51-P03] Analysis of Seismic Waves from Continuous and Controlled Seismic Signal System in Kyushu Area

*松浦 稜祐¹、池田 達紀^2,3、辻 健^1,2,3、山岡 耕春⁴ (1.九州大学大学院工学府共同資源工学専攻、2.九州大学大学院工学府地球資源システム工学専攻、3.九州大学カーボンニュートラル・エネルギー国際研究所、4.名古屋大学大学院環境学研究科地震火山研究センター)

キーワード：人工震源装置、ACROSS、速度変化、SNR

One of the methods to continuously monitor the underground is to use Accurately Controlled Routinely Operated Signal System (ACROSS). By mechanically spinning a weight, this apparatus continuously emits artificial seismic waves, which allows us to know the precise seismic velocity change between the ACROSS and seismometers. By monitoring the difference, underground movements such as earthquakes and volcanic activities can be linked to velocity change, which leads to prediction of such disasters. In this research, we focused on observing P-waves and S-waves which arrived the seismometers located around the ACROSS. Using weight stacking, we stacked maximum 119 days of data to distinguish ACROSS signal from random noises, weighing the signal according to the quantity of noise. By taking the motion of certain direction from the transfer function, different types of waves can be separated, making it easier to analyze in detail. We also investigated signal to noise ratio to clarify how far the signal travels. The result indicates that seismic waves from small-sized ACROSS in Kuju area can be observed 50-100 km far away, and seismic waves becomes clear enough to detect velocity change with 20 days of stacking in stations 10-30 km away. The results of ray tracing demonstrated that observed P-waves can be used to image and monitor the geothermal reservoir and the crustal seismic structure in Kyushu Island.