Late Quaternary Fault Activity Along the Eastern Margin Fault of the Daxing Uplift, Southeast Beijing, China, and Implications for the Rupture Behavior of Intraplate Earthquakes

The mechanisms of seismic rupture behavior for large intraplate earthquakes remain poorly resolved. One important reason is the lack of sufficient paleoseismic data to constrain the spatiotemporal patterns of late Quaternary fault activity. In this study, we used drilling, paleoseismic trenching, radiocarbon dating, and optically stimulated luminescence dating methods to first show that the blind eastern margin fault of the Daxing uplift (EFDU), southeast Beijing, has been active during the Holocene. The most recent paleoseismic event was constrained to have occurred at 6280 ± 250 cal B.P., whereas the fault has showed a low vertical slip rate of ∼0.3 mm/yr since the late Pleistocene. Our results suggest that the fault did not rupture during the M 8 Sanhe–Pinggu earthquake in A.D. 1679, which was associated with the Xiadian fault to the north, indicating a fault segmentation rupture pattern between the two faults. Compared with these two faults and previous results for the North China Plain, we hypothesize that the slowly deforming intraplate active faults might have ruptured less regularly in terms of recurrence intervals. Considering the long-elapsed timing of the blind EFDU, future seismic risk should be a particular focus because of its location in the southern part of the densely populated Beijing Plain.