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The collapse of large impact craters requires a temporary reduction in the resistance to shear deformation of the target rocks. One explanation for such weakening is acoustic fluidization, where impact‐generated pressure fluctuations temporarily and locally relieve overburden pressure facilitating slip. A model of acoustic fluidization widely used in numerical impact simulations is the Block model. Simulations employing the Block model have successfully reproduced large‐scale crater morphometry and structural deformation but fail to predict localized weakening in the rim area and require unrealistically long pressure fluctuation decay times. Here, we modify the iSALE shock physics code to implement an alternative model of acoustic fluidization, which we call the Melosh model, that accounts for regeneration and scattering of acoustic vibrations not considered by the Block model. The Melosh model of acoustic fluidization is shown to be an effective model of dynamic weakening, differing from the Block model in the style of crater collapse and peak ring formation that it promotes. While the Block model facilitates complex crater collapse by weakening rocks deep beneath the crater, the Melosh model results in shallower and more localized weakening. Inclusion of acoustic energy regeneration in the Melosh model reconciles required acoustic energy dissipation rates with those typically derived from crustal seismic wave propagation analysis. Large “complex” impact craters differ in appearance from their smaller, bowl‐shaped counterparts. They are shallower in aspect, with terraced rim walls and an uplifted central mountainous peak or ring of mountains. These differences are the result of dramatic collapse of an initially bowl‐shaped cavity, which only happens in large craters, and is facilitated by temporary weakening of the target rocks. The physical mechanism for this weakening, however, is still debated. One potential weakening mechanism is acoustic fluidization: where impact‐generated vibrations around the crater reduce resistance to deformation until the vibrations dissipate. Computer simulations of large crater collapse that employ this idea have successfully reproduced many observations of large craters on rocky and icy planetary bodies. However, those simulations are yet to replicate rock fracturing in the crater rim region and require that the vibrations persist for much longer than is typical for analogous vibrations produced by earthquakes. By implementing an alternative model of acoustic fluidization we show that the regeneration of vibrations during crater formation facilitates more localized deformation during collapse and explains how vibrations can be sustained around the crater for such a long time. This paves the way for more realistic simulations of crater formation in the future. Acoustic fluidization is a mechanism to explain temporary weakening of target rocks during the collapse of large impact structuresThe Melosh model of acoustic fluidization that accounts for scattering and regeneration of acoustic energy is implemented in the iSALE codeRegeneration of acoustic energy facilitates localized deformation and sustains vibrations for the duration of crater collapse Acoustic fluidization is a mechanism to explain temporary weakening of target rocks during the collapse of large impact structures The Melosh model of acoustic fluidization that accounts for scattering and regeneration of acoustic energy is implemented in the iSALE code Regeneration of acoustic energy facilitates localized deformation and sustains vibrations for the duration of crater collapse

Meteoroid impacts shape planetary surfaces by forming new craters and alter atmospheric composition. During atmospheric entry and impact on the ground, meteoroids excite transient acoustic and seismic waves. However, new crater formation and the associated impact-induced mechanical waves have yet to be observed jointly beyond Earth. Here we report observations of seismic and acoustic waves from the NASA InSight lander’s seismometer that we link to four meteoroid impact events on Mars observed in spacecraft imagery. We analysed arrival times and polarization of seismic and acoustic waves to estimate impact locations, which were subsequently confirmed by orbital imaging of the associated craters. Crater dimensions and estimates of meteoroid trajectories are consistent with waveform modelling of the recorded seismograms. With identified seismic sources, the seismic waves can be used to constrain the structure of the Martian interior, corroborating previous crustal structure models, and constrain scaling relationships between the distance and amplitude of impact-generated seismic waves on Mars, supporting a link between the seismic moment of impacts and the vertical impactor momentum. Our findings demonstrate the capability of planetary seismology to identify impact-generated seismic sources and constrain both impact processes and planetary interiors.