Quaternary activity characteristics of the Qionghua-Liantang fault belt in Hainan.

The Qionghua-Liantang fault belt, located at the boundary between the Fushan depression and the Haikou uplift, is the result of the impact of the uneven extension of the NE-trending Beibu Gulf rift. The Qionghua-Liantang fault belt passes through the Changliu New District and the major projects of the island-looping high-speed railway in Haikou, directly impacting the planning and construction of the Hainan Free Trade Zone. The article uses tectonic geomorphic survey, geophysical exploration, and drilling exploration to reveal that the Qionghua-Liantang fault consists of three NW-trending buried and semi-buried normal faults, which are the Wuyuanhe-Daoxincun fault (F1-1), the Yongzhuangshuiku fault (F1-2), and the Haikouzhuanwachang fault (F1-3). The width of the Qionghua-Liantang fault belt is about 1.8 km, and the length is about 17 km. The vertical displacement of the fault belt is 8.7~41.6 m since the Quaternary. The latest active age of these three faults is the late Pleistocene; the vertical activity rate was less than 0.1 mm/a. It is worth noting that the vertical activity rate of the Haikouzhuanwachang fault (F1-3) is higher than the other two faults and has more vigorous activity. Combining the tectonic background, the latest active age of the Qionghua-Liantang fault, and its relationship with Quaternary volcanic activity, this paper puts forward suggestions on the planning and construction of the Hainan Free Trade Zone and building avoidance of active fault. [ABSTRACT FROM AUTHOR]