Developing Spatial Magnitude Frequency Distributions with LROC NAC Data for Preliminary Lunar Probabilistic Seismic Hazard Assessments

The establishment of long-term crewed installations on the Moon has become a priority by space agencies around the globe, and with those plans it is becoming increasingly important to accurately characterize the hazards faced by longer-lived stations. Probabilistic seismic hazard analysis (PSHA) is used to inform the development of seismic design criteria for terrestrial structures. We now look to leverage PSHA to inform design criteria for future lunar bases. Characterizing the magnitude-frequency distribution (MFD) for seismic hazards is a critical component of a PSHA. Apollo era seismometers, which were active from 1969 to 1977, provided essential information about lunar seismicity, including 28 shallow moonquakes (SMQs) recorded during the operational period. However, the distribution of the instruments on the lunar surface and the sensor performances alone offer limited effectiveness for a PSHA. Imaging from the Lunar Reconnaissance Orbiter Camera (LROC) has facilitated the detection and characterization of very young, surface breaking thrust faults expressed by lobate scarps. Activity on these young faults may be the source of SMQs. Global, high resolution (0.5 mpp) coverage and mapping of lobate scarps allows us to extrapolate the MFD across the entire lunar surface and contextualize the absence of shallow moonquakes detected on the farside of the Moon. In our investigation, we analyzed the spatial correlations between the lobate scarps imaged by LROC and the detected shallow moonquakes. In this study, we provide insights into the significance of clusters of lobate scarps on magnitude distributions, and outline a methodology of using fault maps to help extrapolate limited and localized seismometer information across the entire lunar surface for the development of a global MFD.