# Quaternary Segmentation Characteristics of the Hunhe Fault, Northeast China
## 1 Introduction  
The northern segment of the Tanlu fault zone is an important tectonic unit in Northeast China [1, 2, 3, 4, 5] comprising two main fault branches: the eastern one, known as the Dunhua-Mishan fault zone, and the western one, referred to as the Yilan-Yitong fault zone. Geological evidence suggested that the Yilan-Yitong fault was a Holocene active fault [6, 7, 8], whereas no distinct activity was reported along the Dunhua-Mishan fault since late Pleistocene. The Hunhe fault (Figure 1a), which represents the Liaoning section of the Mishan-Dunhua fault [9, 10] ([PERSON] et al., 2023; [PERSON] et al., 2021), is located south of the modern Hunhe riverbed in the lower Liaone Plain area near Shenyang, exhibiting a concealed nature with an NE-NEE orientation. The development of this fault has a significant impact on regional tectonics and geological evolution [11] ([PERSON] et al., 2016).  
In the vicinity of Fushun, a wide fault zone which constitutes a series of close-spaced faults [13; 14] ([PERSON] and [PERSON], 2020; [PERSON] and [PERSON], 2004) has formed a graben basin, trending NEE, with some local segments approaching an east-west orientation. Although most of the area remains concealed, there are also sections that are exposed. The fault extending from the Fushun Basin eastward to Nanzamu is widely exposed in the low hilly region, exhibiting clear composite branching characteristics with a relatively stable orientation, typically between 75\({}^{\circ}\) and 80\({}^{\circ}\). In the section from Nanzamu to Yingemen, the development morphology of the fault is similar to that of the Fushun section, but its northern and southern branches exert relatively weaker control over the Hunhe graben basin, showing poorer scale and continuity, with significant variations in orientation. The orientation from Nanzamu to Beikouqian is between 70\({}^{\circ}\) and 80\({}^{\circ}\), while the section from Qingyuan to Yingemen exhibits an NE-NEE orientation.  
According to previous studies, the Hunhe fault has been regarded as an active fault from the MIS 20-103 MIS 20-103- MIS6-19 MIS6-19 period, with no significant new activity since MIS 2-5 [15; 16; 17]. However, field investigations reveal significant spatial variability in the tectonic activity of the Hunhe fault. This is not only reflected in the evolutionary history of the fault in different sections but also in the new fault activity since the Quaternary. Some sections even provide geological evidence of the MIS 2-5 period and MIS 2-5 activity,  
Figure 1: **(a)** Simple geological map of the study area. **(b)** The spatial distribution of active faults and destructive earthquakes (419–2019, \(\mathrm{Ms}\geq 4.7\)) in Liaoning and adjacent areas revised from [PERSON] et al. (2007) [12].  
indicating that this fault may show patterns of segmentation, although this remains unclear to date. This uncertainty restricts the assessment of seismic hazards related to the Hunhe fault, highlighting the urgent need for further research to reveal the complexity of its multi-phase activity faults and potential seismic risks.  
This article plans to clarify the precise location and scale of the Hunhe fault through remote sensing interpretation and field investigation. It aims to analyze its detailed structure and activity characteristics, classify the segments of fault activity, investigate the seismic tectonic development characteristics of the Hunhe fault zone, and evaluate the seismic hazard associated with the Hunhe fault.