[S19-2] Apollo seismic data re-processing and future lunar seismology project

[S19-2-04] Source Time Function and Source Parameters of Lunar Quakes and Impacts

^○Taichi Kawamura¹, Philippe Lognonne² (1.National Astronomical Observatory of Japan, Iwate, Japan, 2.Institut de Physique du Globe de Paris, Paris, France)

In this study, we present our result from the spectral analysis and source parameters of lunar quakes and impacts. To improve the spectral analysis, we used both the Apollo long and short seismic data of Apollo. We numericaly combined the two data stream to have a continuous spectrum that covers the both frequency bands. This will enable us to have a broader frequency band than single long or short period seismometer data. We take advantage of the broader frequency band to improve the estimation of spectral features and corresponding source parameters. Here we focused on corner frequencies and DC values of the spectra, which are closely related to stress drops and seismic moments. We first discuss the difference in source time function of quakes and impacts where the former is expressed with a heaviside function and the latter is expressed with a delta prime function. We will discuss how the difference is observed in the actual Apollo seismic data and compare the difference in the seismic signal. Then we will discuss the difference in the scaling law between the corner frequencies and the DC values of spectra. We studied the difference in the scaling low between 3 types of lunar seismic events, which are deep moonquake, shallow moonquake and meteorite impact. We found that not only the scaling law for quakes and impacts differ but that of shallow and deep moonquakes also differ. We conclude with the implication of the different scaling law in comparison with terrestrial examples.