内蒙古地区震源深度测定及构造意义研究OA

Based on the one-dimensional crustal velocity models of three tectonic subregions,western,central and eastern Inner Mongolia,this study adopted the PTD method based on the Pn-Pg travel-time difference to invert the focal depths of earthquake events in Inner Mongolia from 2019 to 2025,with the results verified by the CAP waveform inversion method.Through simulated data tests,the impacts of velocity model errors and phase picking noise on the inversion results were evaluated.The results show that earthquakes in Inner Mongo-lia are dominated by shallow-focus earthquakes with an average depth of 13.6±7.2 km,and the dominant depths are concentrated in the range of 8.5 to 21.0 km.The spatial distribution exhibits distinct zonal character-istics:the focal depths in the Alxa block of western Inner Mongolia are generally deeper with a mean value of 16.2 km;those in the Hetao graben of central Inner Mongolia are significantly shallower with a mean value of 9.7 km;and those in the Greater Khingan Mountains tectonic belt of eastern Inner Mongolia fall in between with a mean value of 12.7 km.This distribution pattern of shallower in the middle and deeper on both sides is highly correlated with the variations in regional crustal thickness and differences in tectonic stress fields.This study provides depth data support for understanding the regional seismogenic environment and the mechanism of strong earthquakes.