Hot spots are critical initiators of both shock-induced detonation and non-shock ignition in explosives， with pore collapse as a primary formation mechanism. Since energetic materials are routinely subjected to complex mechanical loading across a broad intensity range during service， a mechanistic understanding of pore evolution and hot-spot generation under moderate shock pressures （1-10 GPa） is essential for reliable safety assessment. In this study， HMX （octahydro-1，3，5，7-tetranitro-1，3，5，7-tetrazocine） crystals containing a 300 μm prefabricated pore were investigated. High-speed imaging combining X-pinch and visible-light diagnostics captured the dynamic pore collapse process， while thermomechanically coupled numerical simulations accounted for the conversion of plastic work into thermal energy. The results reveal distinct pore collapse modes and associated hot-spot formation mechanisms. At 2.5 GPa， the isotropic pore collapse mechanism was observed， with hot spot intensity correlating positively with the extent of pore collapse. The temperature rise occurs in two stages： an initial gradual increase due to upstream viscoplastic deformation， followed by a sharp temperature rise after pore closure， resulting from the thermal conversion of kinetic energy during the impact of high-velocity upstream material on the downstream pore wall. When the shock pressure is increased to 3.5 GPa， pore collapse initiates earlier， the crescent-shaped deformation becomes more pronounced， and the mechanical response exhibits hydrodynamic behavior， indicating a transition toward jetting-type collapse.