The Seismically Active Lobate Scarps and Coseismic Lunar Boulder Avalanches Triggered by 3 January 1975 (MW 4.1) Shallow Moonquake

P. Senthil Kumar , Rupali Mohanty , K. Jaya Prasanna Lakshmi , S. T. G. Raghukanth , Anjali C. Dabhu , R. P. Rajasekhar, and Rajeev Menon

Like Earth, the Moon is also seismically active but with relatively lesser intensity. The seismometers installed by the Apollo missions detected 28 shallow moonquakes during 1969–1977. The moonquake that occurred at Laue crater on 3 January 1975 is the largest recorded moonquake (MW 4.1). Our analysis of high‐resolution satellite images and topographic data obtained by NASA's Lunar Reconnaissance Orbiter mission aided in the discovery of a set of young lobate scarps near the epicenter and its genetic link to the 1975 moonquake. The moonquake also generated strong ground motion around the epicenter and triggered formation of coseismic boulder avalanches on the interior walls of nearby impact craters. We also found that boulder avalanches were formed during an earlier episode of seismic activity at 1.6 Ma. Furthermore, we deduce that the lobate scarps at Laue crater were formed in response to the reactivation of the basin wall normal fault of Lorentz peak‐ring basin. Our study indicates that the lobate scarps in Laue crater are seismically active and their seismic activity could be further studied during future landing missions.

Geology of the study area: Lunar Reconnaissance Orbiter Camera Wide Angle Camera image mosaic overlain by Lunar Orbiter Laser Altimeter (LOLA) topography

Geophysical Research Letters, 46, 7972–7981. 2019GL083580.