Abstract

Rockfalls or boulder falls on Earth are very common and occur almost daily in certain parts of the world. In contrast, rockfalls on Mars are rare, and no rockfalls have been reported on the Moon in the last decade. This difference underscores the value of studying boulder falls on planetary bodies, as they provide important insights into geological processes. On planetary bodies like Mars and the Moon, millions of boulders/rocks are present on the surface, formed through the weathering of the crust, impact breccia’s, and other geological processes. These boulders vary in size, ranging from a few meters to several tens or even hundreds of meters. On the Moon, these boulders are particularly abundant. To date, using the latest high-resolution images from the Chandrayaan-2 Orbiter High-Resolution Camera (OHRC) and Lunar Reconnaissance Orbiter Narrow Angle Camera (LRO-NAC) there is no report of recent movement of even a single boulder over the past decade. This brings an intriguing question: do all the boulders on the Moon have reached equilibrium, or have there been movements in the last few decades to centuries, which is not been detected to date? How does the detection of movement of boulders help in understanding the recent activities? In this presentation, I will provide evidence for recent boulder falls and their hotspot regions on the Moon related to seismic activity/moonquakes, impact-generated surface shaking, and thermal weathering. Aside from very recent impacts, the primary activity observed on the Moon over the past few decades to centuries is the boulder falls. With the newly identified boulder falls, the Moon joins Earth and Mars, with records of recent boulder falls driven by multiple sources suggesting a sporadically active Moon. Such regions could be potential landing sites for future missions to understand the recent surface/subsurface activity on the Moon.