<p>Iran is located in the collision and compression zone between the Arabian Plate and the Eurasian Plate, where earthquakes occur frequently. The tectonic earthquake in north-central Iran on October 5, 2024, was once questioned as a nuclear explosion, drawing widespread attention. P/S spectral ratio was demonstrated to be an effective method for event discrimination. To distinguish whether an event is abnormal, this study established a basic screening baseline via the P/S spectral ratios from earthquakes in Iran with stations both inside and outside Iran. We firstly investigated the amplitude characteristics of regional seismic phases Pn, Pg, Sn, and Lg in Iran. For Iranian seismic events recorded by stations inside Iran, the Pn, Pg, Sn, and Lg phases are well-developed at most stations. For Iranian seismic events recorded by stations outside Iran, the Pn, Pg, Sn, and Lg phases are well-developed for earthquakes in northwestern Iran at many stations. For earthquakes in southern and east-central Iran, the Pn and Sn phases are developed at some stations, while the Pg and Lg phases are not. Based on the phase attenuation characteristics, we calculated the magnitude and distance amplitude corrected P/S ratios for each stations. According to the corrected Pg/Lg, Pn/Lg and Pn/Sn spectral ratios of earthquakes in Iran, we selected stations with relatively smaller P/S ratios as advantageous stations for screening abnormal seismic events. The distributions of Pg/Lg, Pn/Lg, and Pn/Sn spectral ratios for historical tectonic earthquakes in Iran are presented, providing a baseline for rapidly screening of abnormal earthquakes. We calculated the P/S spectral ratio residuals of the earthquake occurred on October 5, 2024 in north-central Iran. The results show that the P/S ratios of the earthquake are similar to the historical tectonic earthquakes in a common region.</p>