A structural seismic response observation array of the China Earthquake Science Experimental Field (Xichang, Sichuan) is used to investigate the dynamic response characteristics of engineering structures and the seismic input inversion problem under far-field earthquake excitation. An industrial factory building and a multi-story frame-type comprehensive experimental building are selected as the research objects. Structural seismic response data recorded during the March 2025 Myanmar MS 7.9 earthquake were analyzed. An extended Kalman filter (EKF) method was applied to identify unknown seismic input motions and to reconstruct structural dynamic responses.The results show that, in the single-degree-of-freedom industrial factory structure, the identified seismic acceleration time histories are highly consistent with the measured records, and the maximum correlation coefficient exceeds 0.97. In the multi-degree-of-freedom frame structure, only partial floor acceleration observations are used. The maximum correlation coefficients between the identified and measured accelerations at all floors exceed 0.99. The responses of floors not involved in the seismic input estimation are also reconstructed with good accuracy. Comparisons of absolute acceleration response spectra and Fourier amplitude spectra indicate that the identified structural responses well capture the main time-domain and frequency-domain characteristics of the structure under seismic excitation.The results indicate that the seismic input identification and response analysis method based on structural seismic response observation data provides a useful reference for studies on seismic response characteristics of engineering structures and for the analysis of observed seismic data.