Constructing the regional stress profile based on multisource regional stress data and the significance of fault friction strength

The investigation of the regional stress characteristics and frictional strength of geological structures in the Yishu fault belt is of great significance to earthquake prevention and disaster reduction in Shandong province, China. As per the comprehensive collection of geological backgrounds of the Yishu fault belt, we constructed the regional stress profile of it by using hydraulic fracturing in situ stress measurement, high-precision borehole televiewer logging, focal mechanism stress inversion, and modified stress polygon methods. Specifically, there were 152 stress direction data points obtained by using in situ measurements, the maximum horizontal principal stress direction was 92.28°, and the tensile fracture growth phenomenon was found within the test interval range. The regional focal mechanism solution was mainly of the strike-slip faulting type (~ 50%), and the inversion results showed that the stress regime was in favor of strike-slip faulting in the study area. The minimum and maximum lateral pressure coefficients were 0.81 ± 0.19 and 1.24 ± 0.25, 0.86 ± 0.33 and 1.40 ± 0.4, 0.85 ± 0.15, and 1.35 ± 0.35, respectively, in the fairly deep crust of three subzones. The results, consistent with the distribution of b values in the region, indicate that the stress level on the east side of the fault zone is lower than that of the other regions. The crustal dynamic characteristics of the Yishu fault belt, as shown in the stress profile constructed from multisource stress data, can provide an essential basis for regional disaster prevention and mitigation.