Abstract: The surface ruptures produced by the 2016 M_W7.8 Karkoura earthquake, New Zealand are distributed in a belt with~170km long and~35km wide, trending generally in the NE-SW direction. There are at least 12 faults on which meter-scale displacements are identified and they were formed across two distinct seismotectonic provinces with fundamental different characteristics(Hamling et al., 2017; Litchfield et al., 2017). Although the trending directions of the seismic surface ruptures vary greatly at different locations, the ruptured faults can be generally divided into two groups with the NE to NEE direction and the NNW to N direction, respectively. The faults in the NNW-near NS direction are nearly parallel with 40~50km apart and featured by reverse movement with the maximum displacement of 5~6m. The faults in the NE-NNE direction, with the maximum of 25~30km apart are not continuous and featured by the dextral strike slip with the largest displacement of 10~12m. Even if some faults along the NE-NEE direction are end to end connected, their strikes differ by about 30°. The combination styles of the strike-slip fault surface ruptures along the NE-NEE direction can be merged into 3 categories, including en-echelon, bifurcation and parallel patterns. The scales of the fault surface ruptures with the same structural style could be obviously different in different areas, which results in significant changes in the widths of deformation zone, from tens of meters to hundreds of meters. En-echelon distributed surface rupture(section)can appear as a combination belt of meter-scale to dozens of meter-scale shear fracture with bulge and compressional shear fractures, and also can be characterized by the combination of the left-step en-echelon tensile shear fractures with a length of more than one hundred meters. The step-overs between surface rupture sections are clearly different in sizes, which can be dozens of meters, hundreds of meters to several kilometers. The spacing between parallel surface ruptures can be several meters, dozens of meters to several kilometers. Besides, as one of the prominent characteristics, the seismic surface ruptures caused by the Karkoura earthquake broke through the known distribution pattern of active faults. The surface ruptures can occur either on the previously thought inactive or unmapped faults, or break through the distribution range of previously realized active faults in the striking or lateral direction. The basic features about the distribution and widths of the surface ruptures induced by the 2016 M_W7.8 Karkoura earthquake, New Zealand presented in this paper might be helpful for understanding some seismic problems such as complex corresponding relationship between the active faults and the deep seismogenic structure, and the necessary measurements for engineering crossing active faults.

Key words: the 2016 M_W7.8 Karkoura earthquake, fault surface rupture, seismotectonics, safety distance to the active fault

摘要： 新西兰2016年凯库拉M_W7.8地震地表破裂带分布在1个长约170km、宽35km的范围内，总体呈NE-SW走向，至少有12条断裂产生了m量级的地表位错，跨过了2个活动方式与活动强度存在明显差异的地震构造区。地震地表断裂大致可分为NE-NEE向和NNW-近SN向2组，NE-NEE向断裂之间的贯通性差，最大相隔距离为25~30km，即使首尾相连，走向上也有约30°的差异，运动性质以右旋走滑为主，最大位错量10~12m；NNW-近SN向断裂近于平行分布，相距可达40~50km，以逆断裂活动性质为主，最大垂直位错量5~6m。走滑类地表破裂带的组合特征非常复杂，主要表现为3种形式：雁列、分叉和平行分布。其中，雁列地表破裂（段）既可以表现为数m至数十m尺度上的张剪性破裂与鼓包、挤压剪切破裂组合，也可表现为百余m长的左阶斜列张剪性破裂组合；地表破裂段之间阶区规模差异明显，可以是数十m、数百m到数km不等。平行的地表破裂（段）可以相距数m、数十m至数km。凯库拉地震地表破裂带对已知活动断裂分布格局的突破也是1种比较显著的特点，既可以是在原先认为不活动的断裂上或没有活动断裂的位置上产生了地表破裂带，也可以是在走向或横向上突破了先前认识到的活动断裂分布范围。对凯库拉地震地表破裂带发育特征的初步分析结果，对于理解地表活动断裂与深部发震构造之间复杂的对应关系，以及跨活动断裂的抗震设防等问题具有一定的借鉴意义。

关键词: 凯库拉M_W7.8地震, 地表破裂带, 地震构造活动, 断裂避让带