Analysis of solid tide recording capacity of Trillium Horizon 360 ultra-broadband seismometer at Chongli seismic station

Long-period low-frequency waves in seismic records contain crucial information regarding the adjustment of crustal stress states and the mechanical properties of the medium and thus hold significant research value. However, their study was limited by the scarcity of systematic observations. Solid tides, as natural and stable long-period signal sources in geophysics, serve as key indicators for evaluating the low-frequency response performance of instruments. This study, based on the low-noise ultra-wideband reference station built at Chongli seismic station under the National Seismic Intensity Rapid Reporting and Early Warning Project, utilized the continuous observation data from the Trillium Horizon 360 ultra-broadband seismometer deployed there in December 2024 to systematically assess the instrument’s recording capability of solid tides. The results indicate that the instrument can clearly record solid tides, with the observed curves exhibiting good consistency with the theoretical solid tides and relatively good correspondence with the deformation and tilt observations at the same site. This fully confirms the superior observation environment of the Chongli seismic station and demonstrates that the Trillium Horizon 360 seismometer possesses excellent capabilities in observing ultra-low-frequency long-period signals. This has significant implications for recording and studying long-period signals generated by the Earth’s vibrations.