Preliminary analysis of the characteristics of Sichuan Maerkang earthquake swarm on June 10, 2022

On June 10, 2022, a total of five earthquakes of magnitude 4.0 or above occurred in Maerkang City, Sichuan Province, with a total of M_S5.8, M_S4.1, M_S4.4, M_S6.0 and M_S5.2. In this paper, the strong vibration records are filtered and noise reduction treatment, and the attenuation relationships of peak acceleration (PGA), peak velocity (PGV) and spectral acceleration value (Sa) of earthquakes of different magnitudes are compared and analyzed. The acceleration and velocity response spectra of five earthquakes, as well as the Fourier amplitude spectrum, were calculated and compared. The results show that the energy distribution patterns of the five earthquakes are relatively close, and it can be inferred that these series of earthquakes have similar source mechanisms. Due to the inhomogeneity of the station distribution position, the peak acceleration value is higher than the attenuation prediction curve. As the period increases, the decay rate of the actual recorded acceleration and velocity response spectra is faster than that of the attenuation prediction curve. The shape and peak period of the acceleration response spectrum of the same strong motion station in five earthquakes was same. The acceleration response spectrum of the five earthquakes did not exceed the design spectrum of the 7-degree frequently occured earthquake. For earthquakes with high magnitude, the Fourier amplitude spectrum in the frequency range of 0-30Hz is generally higher than that of earthquakes with low magnitude, and it is more significant in some frequency ranges. There is the same characteristic period of the station site by the H/V spectral ratio method and exploration.