Back‐arc basins open in response to subduction processes, which cause extension in the upper plate, usually along trench‐parallel spreading axes. However, global seismic databases reveal that the majority of seismic events in the Lau Basin occur along transcurrent (strike‐slip) rather than extensional faults. To better characterize active deformation in this region, we compared centroid moment tensors (CMTs), calculated for large (Mw > 5), shallow (<30 km) seismic events, to the orientations of seafloor lineaments mapped throughout the Lau Basin. Ship‐based multibeam and satellite altimetry were combined with vertical gravity gradient data to create the lineament map. By comparing the possible focal planes of the CMTs to the orientations of the lineaments, the most likely fault plane solutions were selected, thus classifying the faults and establishing the nature of the highly variable stress regimes in the basin. We resolved the strike, dip, and dip direction of 308 faults and classified 258 additional structures by fault type. The analysis highlights a stress regime that is dominated by a combination of left‐lateral and right‐lateral strike‐slip faults, large‐scale transcurrent motion along rigid crustal‐scale fault zones, and nonrigid diffuse deformation along preexisting seafloor structures, with extension mainly limited to the tips of propagating rifts and spreading centers. By resolving many of the uncertain motions on the mapped lineaments of the Lau Basin, the CMT analysis addresses a number of questions concerning basin‐scale stress regimes and microplate development, complementing GPS measurements, and providing a more complete picture of the complexities of back‐arc basin development.

中文翻译：

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刘后弧盆地浅层地震活动与构造分类

弧形盆地因俯冲作用而打开，通常导致沿上沟平行的扩展轴在上板伸展。但是，全球地震数据库显示，劳盆地的大部分地震事件都是沿着横流（走滑）而不是伸展断层发生的。为了更好地表征该区域的主动变形，我们将针对大地震（Mw> 5），浅地震（<30 km）计算出的质心矩张量（CMT）与整个Lau盆地海床构造的方向进行了比较。将基于船的多波束和卫星测高与垂直重力梯度数据相结合，以创建线状图。通过将CMT的可能焦平面与谱线的方向进行比较，选择了最可能的断层平面解，从而对断层进行分类，并建立盆地中高度变化的应力状态的性质。我们解决了308个断层的走向，倾角和倾角方向，并按断层类型分类了258个其他结构。分析强调了一种应力状态，该状态主要由左右走滑断层，沿刚性地壳断层带的大规模横流运动以及沿既有海底结构的非刚性弥散变形共同作用所主导，仅限于传播裂口和扩散中心的提示。通过解决Lau盆地图线上的许多不确定运动，CMT分析解决了与盆地尺度应力模式和微孔板发育有关的许多问题，补充了GPS测量，