The North Basin of the Malawi Rift is an active, early‐stage rift segment that provides the opportunity to quantify cumulative and recent faulting patterns in a young rift, assess contributions of intrarift faults to accommodating rift opening, and examine controls on spatial patterns of faulting. Multichannel seismic reflection data acquired in Lake Malawi (Nyasa) in 2015 together with legacy multichannel seismic data image a system of synthetic intrarift faults within this border‐fault‐bounded, half‐graben basin. A dense wide‐angle seismic reflection/refraction dip profile acquired with lake bottom seismometer data constrains sediment velocities that are used to convert fault throws from travel time to depth. Observed extension on intrarift faulting in the northern and central parts of the North Basin is approximately twice what would be predicted for hanging wall flexure, implying that the intrarift faults contribute to basin opening. The cumulative throw on intrarift faults is higher in the northern part of the rift segment than the south and is anticorrelated with throw on the border fault, which is largest in the southern part of the North Basin. This change in faulting coincides with a change in the orientation of the North Basin from a N‐S trend in the south to a NNW‐SSE trend in the north. We infer that the distribution of extension is influenced by rift orientation with respect to the regional extension direction. Almost all intrarift faults substantially offset late Quaternary synrift sediments, suggesting they are likely active and need to be considered in hazard assessments.

中文翻译：

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东非马拉维（尼亚萨）大裂谷北部盆地的裂谷断层控制

马拉维裂谷的北部盆地是一个活跃的早期裂谷段，它提供了量化年轻裂谷中累积的和最近的断层模式，评估裂谷内断层对适应裂谷开放的贡献以及检查对断层空间模式的控制的机会。 。2015年在马拉维湖（尼亚萨）获得的多通道地震反射数据与旧有的多通道地震数据一起成像，表明该边界断裂带边界的半盆盆地内有一个合成的裂谷断层。用湖底地震仪数据采集的稠密广角地震反射/折射倾角剖面图约束了泥沙速度，这些泥沙速度用于将断层抛物从行进时间转换为深度。在北部盆地北部和中部观察到的裂谷内断裂的扩展程度约为壁挂挠曲预测值的两倍，这表明裂谷内断层有助于盆地的开放。在裂谷段的北部，裂谷内断层的累积投掷比南部高，并且与边界断层的投掷呈反相关，边界断层的投掷在北盆地的南部最大。断层的这种变化与北部盆地的方向从南部的N-S趋势到北部的NNW-SSE趋势变化相吻合。我们推断，扩展的分布受到相对于区域扩展方向的裂谷定向的影响。几乎所有的裂谷内断层都基本上抵消了第四纪晚期的裂谷沉积物，