The seismically active lobate scarps and co‐seismic lunar boulder avalanches triggered by 3rd January 1975 (MW 4.1) shallow moonquake

On 3 January 1975, the largest shallow moonquake (M-W 4.1) occurred at Laue impact crater on the Moon. The fault responsible for the moonquake and origins of coseismic boulder avalanches are unknown. Our study reveals a set of previously unreported, seismically active, young lobate scarps near the epicenter. In addition, hundreds of boulder falls are observed on the interior walls of two impact craters on either side of the lobate scarps. The varying preservation levels and crater size-frequency distributions of impact craters superimposed on the boulder falls indicate their episodic origins at 1.6 Ma and during the 1975 shallow moonquake. Our ground motion simulations confirm that the M-W 4.1 moonquake along the lobate scarp at 1- to 5-km focal depths produced strong ground shaking that triggered the boulder avalanches. Also, the fault slip along the Lorentz basin wall beneath the Laue crater floor produced the lobate scarps and the shallow moonquakes.