Abstract:We use the harmonic amplitude ratio method to analyze the fluxgate second sampling observation data in Qinghai area. On this basis, we apply the rate accumulation method to analyze the daily change rate of continuous data. Then, according to the need to identify the abnormal changes of data, we carry out the accumulation calculation of the analysis period. We further analyze the relationship between the abnormal change and strong earthquake, and summarize the characteristics of harmonic amplitude ratio of fluxgate second value in Qinghai region so as to complete the process from qualitative to quantitative recognition of anomalies. The results shows that the curves of the geomagnetism harmonic amplitude ratio after rate accumulation processing are continuously rising to normal, while the curves are continuously decreasing and the horizontal fluctuation are abnormal. When the duration of the anomaly is more than 1 a and the number of anomalous curves is more than half, the probability of M≥5 earthquakes around the station is high, and the curve period mainly ranges from 20 to 170 s. The magnitude is proportional to the epicenter distance, that is, the higher the earthquake magnitude, the greater the epicenter distance.
LI Xia,FENG Lili,ZHAO Yuhong et al. Anomaly Indicators Extracted of Geomagnetism Harmonic Amplitude Ratio Based on Rate Accumulation Algorithm[J]. jgg, 2022, 42(3): 303-311.