Recent boulder falls within the Finsen crater on the lunar far side: An assessment of the possible triggering rationale

• Published in: Icarus
• Main Authors: RUJ T., KOMATSU G., KAWAI K., OKUDA H., XIAO Z., DHINGRA D.
• Other Authors: Ruj, T., Komatsu, G., Kawai, K., Okuda, H., Xiao, Z., Dhingra, D.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2022
• Subjects: South pole
• Online Access: http://hdl.handle.net/11564/765388; https://doi.org/10.1016/j.icarus.2022.114904; https://www.sciencedirect.com/science/article/pii/S0019103522000264?via=ihub

To better understand the necessary triggers for the origin of the lunar boulder tracks, we report 650 tracks from the ~73 km in diameter Finsen crater. The tracks were identified on the crater wall and the central peak region of the Finsen crater, located within the South Pole ̶ Aitken basin on the lunar far side. In this manuscript, we assessed two main possibilities of triggers, 1) ground shakings by the recent meteorite impact, and 2) ground shaking from recent fault reactivation associated with the lobate scarps identified inside and in the vicinity of the Finsen crater. Our assessments revealed that the impact-induced seismicity could have generated the moonquake with the maximum moment magnitude (MW) 4.63. We also estimated that the moonquakes excited by the movements along the lobate scarps had an estimated cumulative (or maximum possible) moment magnitude (MW) up to 6.86 and 6.90, i.e., for the basaltic and noritic basement respectively. Considering the location of the Finsen crater positioned over the structural discontinuity along the boundary of the central and mid rings of the South Pole ̶ Aitken basin and higher moment magnitude generated from the fault movements, we propose that the region is potentially seismotectonically active, and reactivation of pre-existing faults possibly triggered/triggers the necessary ground motion for the boulders to initiate their movements. However, impact-induced ground shakings and deep-focused moonquakes also remain possibilities for triggers.