Frequency domain characteristic information of seismic events in superconducting gravity measurement data

Abstract

The accuracy of superconducting gravimeter can reach 0.1 μGal, which is an important basis for acquiring the frequency domain characteristics of gravity changed by earthquakes. Based on the observation data of the iGrav-012 superconducting gravimeter in National Institute of Metrology, China, we performed the variation characteristics of the dominant frequency band of the gravity disturbance signal before and after the earthquake event with the magnitude and epicenter distance using the spectral analysis method. The study showed that for distant epicenters above magnitude 4, the impact of magnitude and epicentral distance on the coseismic response and dominant frequency bands of superconducting gravity data in different time windows before and after the earthquake is not significant. The occurrence of earthquakes has a modulating effect on the frequency domain components of superconducting gravity earthquake pre- and post-earthquake data. That is, the number of spectral peak centers and the spectral peak center frequency of the PSD curve in the time window of 1 hour before the earthquake and 1 hour after the earthquake will change. There is no significant pattern in the number of spectral peak centers and the frequency of spectral peak centers in the PSD curve of superconducting gravity data during coseismic periods. This provides a new understanding of the in-depth analysis of gravity field change information caused by high-frequency internal activities of the Earth, and reveals the application prospects of dynamic monitoring of earthquake breeding and occurrence processes based on frequency domain feature analysis of high-precision superconducting gravity data.

Keywords

• superconducting gravity measurement
• seismic gravity disturbance
• spectral analysis
• frequency domain characteristics