Most active block boundary faults within the Tibetan plateau have been thought of as Holocene active, and are able to produce large earthquakes. However, it is unknown whether the Jiali fault (JLF) has been seismically active in the Holocene, which currently hampers efforts to undertake meaningful seismic hazard assessments near the southeastern part of the Tibetan plateau. In this study, it is shown that the JLF has indeed ruptured during the Holocene, as evidenced from geological, paleoseismic, and radiocarbon dating investigations. Specifically, at least two surface‐rupturing paleoseismic events were revealed with ages between $2160±30yr$ B.P. and $2680±30yr$ B.P., and prior to $2730±30yr$ B.P., respectively. Combined with previous studies on the JLF, we suggest that the fault (1) can be considered an active block boundary fault and (2) accommodates crustal deformation related to the uplift of the Tibetan plateau since the late Cenozoic.

The rupture behavior of large‐scale thrust faults has become an increasingly important topic in active tectonic and seismic studies. This is especially true for the 2008 Wenchuan earthquake (Mw 7.9), which occurred along the Longmenshan thrust fault (LMS) in China. While this earthquake has been the subject of many studies to date, paleoseismic studies along the LMS are still lacking. In this study, results from trenching at the town of Bailu, as well as radiocarbon and Optical‐Stimulated Luminescence dating, are used to constrain the timing of the penultimate and earlier events, respectively: 3.3 ± 0.6 to 4.4 ± 0.6 ka and 4.8 ± 0.6 to 5.8 ± 0.8 ka. Further, coseismic displacement produced by the two events is similar to that produced by the 2008 event. The results suggest that fault segments along the Yingxiu‐Beichuan and Jiangyou‐Guanxian faults likely ruptured coseismically with similar offsets and that the northern segment of the LMS possesses independent rupture behavior. The magnitude of the penultimate seismic event was likely lower than that of the 2008 event, which indicates a characteristic slip‐rupture pattern along the LMS.

In mainland China, approximately 86% of $M≥7$ earthquakes have occurred in the block boundary zone, which has been well explained by active block theory. However, a few large earthquakes have occurred within the active block, which provides us with an opportunity to better study the deformation of the Tibetan Plateau. The Litang Fault (LTF) is a strike-slip fault within the Sichuan-Yunnan Active Block and produced the 1948 Litang M7.3 earthquake. We presented the Holocene rupture behavior of the LTF based on detailed field investigations, paleoearthquake trenching, and radiocarbon dating. Specifically, we revealed 13 Holocene paleoearthquake events at four trenching sites and divided these events into 3 rupture cycles at the whole-fault scale. The seismic rupture behavior of the LTF is characterized by recurrent southeastward migration, and since the Holocene, the period of each rupture cycle has decreased rapidly from 8000 years to 500 years. Our results may provide geologic evidence for understanding the intrablock stress patterns and material transfer of the southeastern region of the Tibetan Plateau. The rapidly enhanced fault activity of the LTF since the late Holocene indicates that the LTF may have played an important role in accommodating the deformation of the southeastern region of the Tibetan Plateau.

The Qingchuan fault is located along the eastern margin of the Tibetan Plateau and connects to the Beichuan‐Yingxiu fault of the Longmen Shan fault zone (LMSF), which produced the 2008 M_W 7.9 Wenchuan earthquake and 2013 M_W6.6 Lushan earthquake. After the two devastating earthquakes, whether the Qingchuan fault could produce a large earthquake or not and its tectonic activity is highly debated. Based on the detailed field investigations and paleoseismic trenching combined with multiple radiocarbon dating, we suggest that the Qingchuan fault might not show intense fault activity (or specific dextral strike‐slip deformation) since the late Quaternary. The deformation evidence revealed in the trench indicates a pattern of tensional deformation in the strata, which is inconsistent with the regional compressional tectonic stress field. Moreover, the timing of these deformation events coincides with that of paleoearthquakes that occurred on the Beichuan‐Yingxiu fault. Therefore, we speculate that the large earthquakes that occurred on the northern segment of the Beichuan‐Yingxiu fault highly likely contribute to the formation of the tensional structures observed along the Qingchuan fault. The uplift of the Minshan Mountain affects the tectonic deformation and seismic activity of the northern segment of the LMSF. However, considering that the LMSF shows forward‐thrust characteristics, the fault activity of the Qingchuan fault was possibly the most affected by the uplifting of the Minshan Mountain. In other words, this specific regional tectonic frame might constrain the buildup of tectonic stress and seismic potential for generating large earthquakes on the Qingchuan fault.