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Recent shallow moonquake and impact‐triggered boulder falls on the Moon: New insights from the Schrödinger basin
Author(s) -
Senthil Kumar P.,
Sruthi U.,
Krish.,
Lakshmi K. J. P.,
Me Rajeev,
Gopala Krishna B.,
Kring David A.,
Head James W.,
Goswami J. N.,
Kiran Kumar A. S.
Publication year - 2016
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
eISSN - 2169-9100
pISSN - 2169-9097
DOI - 10.1002/2015je004850
Subject(s) - fault scarp , geology , impact crater , structural basin , tectonics , geomorphology , seismology , astrobiology , physics
Shallow moonquakes are thought to be of tectonic origin. However, the geologic structures responsible for these moonquakes are unknown. Here we report sites where moonquakes possibly occurred along young lobate scarps in the Schrödinger basin. Our analysis of Lunar Reconnaissance Orbiter and Chandrayaan‐1 images revealed four lobate scarps in different parts of the Schrödinger basin. The scarps crosscut small fresh impact craters (<10–30 m) suggesting a young age for the scarps. A 28 km long scarp (Scarp 1) yields a minimum age of 11 Ma based on buffered crater counting, while others are 35–82 Ma old. The topography of Scarp 1 suggests a range of horizontal shortening (10–30 m) across the fault. Two scarps are associated with boulder falls in which several boulders rolled and bounced on nearby slopes. A cluster of a large number of boulder falls near Scarp 1 indicates that the scarp was seismically active recently. A low runout efficiency of the boulders (~2.5) indicates low to moderate levels of ground shaking, which we interpret to be related to low‐magnitude moonquakes in the scarp. Boulder falls are also observed in other parts of the basin, where we mapped >1500 boulders associated with trails and bouncing marks. Their origins are largely controlled by recent impact events. Ejecta rays and secondary crater chains from a 14 km diameter impact crater traversed Schrödinger and triggered significant boulder falls about 17 Ma. Therefore, a combination of recent shallow moonquakes and impact events triggered the boulder falls in the Schrödinger basin.