The slip rate is a fundamental kinematic parameter of active faults. Traditional methods using fault scarps or trenches may produce inaccurate estimates of a fault’s vertical slip rate. A normal fault’s vertical slip rate requires constraints from the hanging wall and footwall. Here, the vertical slip rate at each measuring point along the fault was calculated by the joint constraints of terraces in the footwall and boreholes in the hanging wall. Nine measuring points were selected along the Sertengshan piedmont fault. The vertical slip rates of this fault since 65 and 12 ka were 0.74–1.81 and 0.86–2.28 mm/a, respectively. Four measuring points were selected along the Wulashan piedmont fault. The vertical slip rates of this fault since 60 and 12 ka were 2.14–3.11 and 1.84–2.91 mm/a, respectively. Seven measuring points were selected along the Daqingshan piedmont fault; the vertical slip rates were 2.5–3.88 and 1.78–2.83 mm/a since 58 and 11 ka, respectively. Analysis of the slip rates, the elapsed time since the last palaeoearthquake and the mean recurrence interval of palaeoearthquakes on each fault segment on the northern margin of the Hetao Basin suggests that the Langshankou and Hongqicun segments of the Sertengshan piedmont fault are at higher risk of earthquakes than the other segments. Among the fault segments of the Wulashan piedmont fault, the Baotou segment is at the highest seismic risk. The seismic risk of the Tuyouxi segment of the Daqingshan piedmont fault should not be ignored, and the Tuzuoxi, Bikeqi and Hohhot segments have high seismic risk. Based on the findings and a dynamic model of the formation and evolution of the Ordos block, it is concluded that the depositional centre of the Hetao Basin has tended to migrate from west to east. The vertical force generated by deep material movement is the dominant factor leading to a greater vertical slip rate in the eastern portion of the northern margin of the Hetao Basin. The modern stress field in the Hetao Basin results in an increase in the vertical slip rate of active faults from west to east along the northern margin of the basin.

Understanding the earthquake recurrence patterns of active faults and evaluating regional seismic hazards require long-term paleoearthquake records. Deformation recovery analyses of trenches and quantifications of various evidence related to earthquake events can more objectively evaluate the reliability of earthquake events without omitting information on sedimentology and tectonic deformation (Liu et al., 2021;Xu et al., 2019). Seitz (1999) first classified evidence for earthquake events at a trench site on the San Andreas fault at Pitman Canyon to discuss the credibility of paleoearthquake events. Scharer et al. (2007Scharer et al. ( , 2017 further classified evidence for paleoearthquake event identification and described in detail the characteristics of this evidence at different levels. This method is currently primarily applied to large strike-slip faults, such as the San Andreas fault (Scharer et al., 2017), Haiyuan fault (Liu-Zeng et al., 2015), and Altyn Tagh fault (Yuan et al., 2018), and has not yet been used to study paleoearthquakes on normal faults. The classification and scoring of evidence of paleoearthquake events on normal faults can enhance the objectivity of paleoearthquake event identification, which is conducive to applying and evaluating the research results of later researchers. The Hetao Basin is an important seismic

The response of the stream geomorphic index to fault activity is important for assessing the regional seismic hazard. The data used in this paper are 12 m resolution TanDEM-X data. The Fill tool in the Hydrology toolset in ArcGIS 10.5 was used to first process the digital elevation model (DEM), then analyse the flow direction of the DEM after filling and finally extract streams with catchment areas of more than 9 km2. Based on the DEM spatial analysis, the stream geomorphic index of the Lianfeng–Ningnan segment (LNS) of the Lianfeng fault was extracted, including the stream length gradient (SL) and the hypsometric integral (HI). This information, combined with the analysis of typical field geomorphology and terrace profiles, was used to define the fault activity period. To analyse the activity characteristics of the LNS, the LNS was divided into northern (Lianfeng to Jinyang), middle (Jinyang to Duiping town) and southern segments (Duiping town to Ningnan). The stream geomorphic index showed spatial variations, with mean SL and HI values of 384 and 0.45, respectively, in the northern segment; 175 and 0.41, respectively, in the middle segment; and 378 and 0.45, respectively, in the southern segment. These results indicate that the northern and southern segments of the LNS are more active than the middle segment, that there is little difference between the northern and southern segments, and that the activity of the middle segment is relatively weak. By comprehensively analysing the lithology, climate and tectonics in the LNS region, we conclude that tectonics are the main factor controlling the stream geomorphology in the LNS region. Based on this information and the analysis and dating of field geomorphology and terrace profiles, we found that the Lianfeng fault was active in the Holocene, which is consistent with the latest research results.