Active Normal Faulting along the Langshan Piedmont Fault, North China: Implications for Slip Partitioning in the Western Hetao Graben.

The northwestern margin of the Hetao Graben, North China, is bounded by a pronounced 160-km-long Langshan Piedmont fault (LPF). The kinematics and recent tectonic activity of this rift-border fault and its accommodated extensional strain can help us better assess the seismic potentials. In this study, on the basis of high-resolution satellite images, digital elevation models acquired by small unmanned aerial vehicles using structure-for-motion techniques, field observations, and radiocarbon (14C) age dating, we demonstrate that (1) the LPF is a Holocene active normal fault with an average dip of ~607; the extension rate is estimated to be ~0.4-0.7mm/y, lower than geodetic strain rate; (2) the ongoing tectonic activity along this fault has played a significant role in controlling the present topography of the Langshan Mountains and neighboring areas; (3) slip partitioning probably occurred in the western Hetao Graben; namely, normal slip dominated the basin-bounding faults, and right-lateral slip occurred on the buried faults within the flat-lying graben. We suggest that precisely determined fault slip rates and geometry are needed with the aim of further quantifying the extensional strain distribution. The results of this study would be helpful in achieving a better understanding of fault development and evolution in actively extending regions. [ABSTRACT FROM AUTHOR]