Hydrocode Simulation of Lonar Impact Event: Insights Into Brittle Deformation and Formation of Simple Craters in Basalt

Abstract

The Lonar crater is one of the few well‐preserved impact craters on Earth and provides an important analog for impact processes in basaltic targets. We model the Lonar impact event using iSALE‐2D simulations incorporating ANEOS basalt–dunite equations of state, rock strength, and resolution tests to determine the transient crater dimensions, shock pressure, strain distribution, and fracture formation, bridging numerical simulations with field observations. The best‐fit model produces a transient cavity ∼1,415 m in diameter and ∼530 m in depth at ∼5 s after impact, evolving into a final crater ∼1,900 m in diameter. Peak shock pressures of ∼10 GPa and temperatures of ∼1000 K occur at the crater floor, while pressures of 2–3 GPa occur at the crater wall. The simulation tracks the progressive formation of near‐surface fractures followed by radial and concentric fractures, accompanied by zones of high plastic strain near the crater floor. By linking the modeled deformation with field‐documented fracture geometries, this study provides new constraints on the mechanical and thermal evolution of Lonar‐scale impact craters in basaltic targets. Modeled pressure conditions at the crater wall agree with the field occurrence of a shatter cone. Comparison with empirical scaling relations and resolution tests demonstrates that the crater dimensions, shock field, and fracture architecture are robust and converge at resolutions of CPPR ≥ 20. These results refine constraints on the formation conditions of the Lonar crater and provide a modeling framework for interpreting impact cratering in basaltic terrains on Earth and other planetary bodies.