Abstract:This study systematically collected and organized seismic intensity isopleth maps and relevant damage investigation data for 44 seismic events in the Loess Plateau region.We employed a constrained model of seismic intensity ellipses and applied two-step regression with double weighting to establish seismic intensity attenuation relationships for both the western and eastern regions of the Loess Plateau. By imposing additional fitting constraints, we achieved the requirement of approximately equal intensity values for the major and minor axes at epicentral and far-field distances. Comparative analysis with seismic intensity attenuation relationships in other regions revealed distinct regional characteristics in the Loess Plateau area. In most cases, at equivalent distances, the intensity values in the western region of the Loess Plateau are higher than those in the Qinghai-Tibetan Plateau, with a maximum difference of 0.8 degrees. For short epicentral distances, both major and minor axis intensity values in the eastern region of the Loess Plateau are lower than those in the eastern strong earthquake zone. Due to the slower attenuation rate of intensity in the Loess Plateau"s eastern region, as the distance increases, the intensity values in the eastern region gradually surpass those in the eastern strong earthquake zone.
