Bounds on the Holocene Slip Rate of the Haiyuan Fault, North-Central China

Abstract

We measured the offsets of six stream valleys, of 30 to 90 m, along the northwest-southeast trending, left-lateral Haiyuan strike-slip fault, in north-central China. Minimum ages of these offsets were determined to estimate lower bounds for the Holocene slip rate. The most reliable bounds are 7.6 ± 1.0 and 6.7 ± 1.0 mm/yr, with three others that are smaller (3.4 ± 0.7, 3.5 ± 0.9, and 4.1 ± 0.4 mm/yr) and one large value (16.4 ± 5.9 mm/yr) that we doubt. Thus, the average Holocene slip rate of the Haiyuan fault is larger than 6 mm/yr and probably exceeds 7 mm/yr. If the average slip rate of 5 to 10 mm/yr for the Quaternary Period is applicable to the Holocene Epoch, the average rate is 8 ± 2 mm/yr.