Abstract：Before the Qinghai Maduo MS7.4 earthquake, the VP broadband tiltmeter of Anxi seismic station in Gansu province showed obvious abnormal changes and recorded co-seismic waveforms. Combined with the CTS-1 seismometer for fusion analysis, the phase of co-seismic waveforms changed in the same time, showing that the records of two sets of instruments are reliable and consistent, but the characteristics of seismic phase differ. The annual change is broken and tilts to the northwest on April 17, 2021, when analyzing the data of the VP broadband tiltmeter, and the original northwest tilt is restored to the southwest tilt on May 13. The azimuth of sharp increase of dip angle recorded before the earthquake is consistent with that from the epicenter to the station, and the change of tilt rotation is consistent with the direction of regional tectonic stress. The time-frequency spectrum of hour data show low-frequency signals from 1.085×10-6 to 4.340×10-6 Hz(period 64~128 h). There are significant differences in the dominant frequency and time-frequency variation characteristics of the two sets of instruments in the earthquake, which may be related to the different mechanical structures, frequency band widths, and sampling frequencies of the two sets of instruments.
YAN Xun,GAO Shude,JIANG Zhenhai et al. Data Characteristics Analysis of VP Broadband Tiltmeter of the Anxi Station to the MS7.4 Earthquake in Maduo, Qinghai[J]. jgg, 2022, 42(8): 874-880.
