Abstract:We use the original curve analysis and normalized rate method to analyze the changes of three earth resistivity data sets within 300 km from the epicenter of Menyuan earthquake. Judging from the original curve, the EW component of Jinyintan station has a sharp jump and a downward trend of retaining annual change (-3.3%) in the two months before the earthquake. The NS component of Shandan station has a downward trend (-1.9%), and the EW component has an upward trend (3.1%). The NS component of Wuwei Xiaoxigou station has a downward trend (-3.3%), the EW component has an upward trend (2.8%), and the trend of EW component turned flat after the earthquake. The normalized rate curves of the three earth resistivity stations all exceeded the threshold before the Menyuan earthquake, but their normalized rate patterns are different. The sudden change of the hour value, the accelerated change of the daily average and monthly average values, and the turning change, especially the turning change in the stage of rising to the high value, which can be analyzed as an abnormal shape. When the above changes are not obvious, the normalized rate method should be combined to extract the abnormality.
YAO Saisai,GAO Shude,CHEN Xuemei et al. Analysis of Earth Resistivity Changes before the 2022 Qinghai Menyuan MS6.9 Earthquake[J]. jgg, 2023, 43(2): 141-147.