Active faults and dip slip rates along the northern margins of the Huashan Mountain and Weinan loess tableland in the southeastern Weihe Graben, central China

Two active faults, including the Huashan piedmont fault (HPF) along the northern margin of Huashan Mountain and the north margin fault of the Weinan loess tableland (NMF-WLT), were developed in the southeastern Weihe Graben, in central China. HPF, which is the most active fault in the Weihe Graben, is known throughout the world for the M8 1/4 great Guanzhong earthquake in 1556 AD. Through field investigation, AMS C-14, and OSL dating in this paper, in combination with previous studies, the following results are obtained: (i) Tectonic landforms, such as triangular fault facets, waterfalls and fault scraps of proluvial fans, were developed in the HPF, but these features were not developed in the NMF-WLT. (ii) HPF experienced three intensive seismic activities in 5920-7670 Cal yr BP, 2215 +/- 95-3105 +/- 105 Cal yr BP and 1556 AD during the Holocene, but there has only been one seismic event noted for the NMF-WLT since the Holocene (6865 +/- 80 Cal yr BP). (iii) The dip-slip rate of the HPF was approximately 0.64 mm/yr since the mid-Pleistocene and approximately 1.67-2.71 mm/yr in the Holocene. In contrast, the dip-slip rate of NMF-WLT was approximately 0.32-0.42 mm/yr since the early Pleistocene and was approximately 0.39-0.58 mm/yr from the late Pleistocene to the Holocene. (iv) The seismic activity at the HPF has been more intense than at the NMF-WLT; the HPF was the triggering seismic fault of the M8 1/4 great Guanzhong earthquake in 1556 AD, whereas the NMF-WLT was not the seismogenic fault of this event. These results provide new information for the study of active tectonics of the Weihe Graben. (C) 2015 Published by Elsevier Ltd.