Seismic Signal Detection and Analysis of the May 4 Liuyang Fireworks Factory Explosion Using the DiTing Seismogram Foundation Model

On May 4, 2026, a massive explosion occurred at a fireworks factory in Liuyang, Hunan Province, China. In this study, the DiTing seismogram foundation model (DT-SFM) was used to detect and analyze three-component continuous 24-h waveform data recorded at Liuyang seismic station (LIY), approximately 39 km from the explosion site, on the day of the incident. The origin time, apparent epicentral distance, back azimuth, and classification results were combined to preliminarily identify two explosion events, at 16:42 and 16:50 local time (UTC+8). Waveform characteristics were compared with those of a natural earthquake and a collapse event located close to the explosion site and also recorded at LIY. For the two explosion events, the energy density was predominantly distributed below 10 Hz, and waveform durations were relatively long; S-wave energy was concentrated in the frequency range of 0.5–1.6 Hz, whereas P-wave spectrum exhibited a bimodal distribution (0.5–1.4 Hz and 3.0–4.5 Hz). Differences between event types were attributed to multiple factors, including the source, propagation path, site conditions, and ambient noise. Single-station local magnitudes calculated for the two explosion events were M_L1.4 and M_L1.6. Considerable uncertainties arose when using different empirical magnitude–yield relationships to estimate the TNT-equivalent explosive yield. In summary, DT-SFM enables the rapid detection and preliminary analysis of weak single-station seismic signals generated by sudden industrial explosions under low signal-to-noise ratios.