Microseismic Noise before and after Strong Earthquakes: Case Study of Chilean Subduction Zone

Abstract—In this work, we study the parameters of microseismic noise in the vicinity of the Chilean subduction zone in order to detect oscillations of a block–fault system, similar to those identified by processing the results of the previous laboratory experiment. The analysis is based on the data recorded by the broadband seismic stations of the international seismic network IRIS. We calculated the spectral parameters of microseismic noise before and after several earthquakes. It is established that before the earthquakes with Мw ≥ 8, the calculated value of spectral centroid decreases by 0.12–0.26 Hz. The decrease in the value of spectral centroid in the range from 0.008 to 0.45 Hz can be as long as up to two days. The proposed approach can be a new instrument useful for real-time monitoring of active faults of various scales.