<p>Approximately one hour after the 2024 M7.6 Noto Peninsula earthquake, a large-scale urban fire erupted in Kawai-machi, Wajima City, central-northern Japan. In the absence of a clearly identified surface ignition source, previous work (Enomoto et al., Npj Nat Hazards 2, 2025) proposed that the fire may have originated from subsurface processes. This interpretation was supported by analyses of historical records of earthquake-induced fires, media footage, geological literature, field observations, and chemical measurements of groundwater gases, which collectively suggest that methane released from underground reservoirs may have contributed to this unprecedented event. However, the mechanism responsible for the approximately one-hour delay between the mainshock and ignition has remained unresolved. The present study examines anomalous ground-motion amplification associated with an aftershock that occurred nearly simultaneously with the fire in Wajima. Quantitative analyses of seismic acceleration waveforms and amplitude spectral distributions reveal a time-dependent cascade involving resonance-enhanced degassing, diffusion-controlled growth of dissolved gas bubbles, upward gas migration, accumulation and pressure build-up beneath shallow low-permeability layers, and eventual failure of near-surface sediments, here termed the delayed seismic champane effect. These processes are consistent with a delayed sequence of subsurface gas dynamics following strong seismic shaking, which may have contributed to the conditions leading to the urban fire. The findings highlight the potential for earthquake-induced subsurface gas processes to generate delayed, non-tectonic hazards during the post-earthquake phase.</p>