The giant tsunami that swept the Pacific from Alaska to Antarctica in 1946 was generated along one of three Alaska Trench instrumentally recorded aftershock areas following great and giant earthquakes. Aftershock areas were investigated during the past decade with multibeam bathymetry, ocean bottom seismograph wide‐angle seismic, reprocessed legacy, and new seismic reflection images. Summarized and updated here are previous papers and additional data. Tectonic structures collocated with aftershock area boundaries indicate possible lengths of rupture in future great earthquakes. NE aftershock area boundaries relate to subducted lower plate structures whereas the SW zone upper plate retains Beringian structural relicts. The lower to middle slope transition separating a stronger continental framework rock from a weaker accreted prism occurs along splay fault zones previously interpreted as backstops in seismic images. Damage zones along splay faults are generally 1‐km‐wide dipping typically 21°. Splays form slip paths from the plate interface to the seafloor much shorter than the 3–4° dipping plate interface beneath the frontal prism. Associated seafloor vent structures indicate overpressured fluids at depth. Splay fault dip and its rigid hanging wall impart greater seafloor uplift than the accreted prism per unit of slip making them effective tsunami generators. Backstop splay fault zones (BSFZs) run along the entire Alaska Trench. Beneath the frontal prism, active bend faults add rugosity to the plate interface and km high relief is commonly imaged in reprocessed legacy and new seismic data. The 1946 Unimak great (M8.6) earthquake epicenter is located near the BSFZ.

中文翻译：

---

阿拉斯加会聚边缘逆止扩张断裂带，是潜在的大型海啸发生器，位于前棱镜和大陆架之间

1946年，大海啸席卷了太平洋，从阿拉斯加席卷到南极洲，是沿着大地震和大地震在仪器记录的三个阿拉斯加海沟之一中产生的。在过去的十年中，对余震地区进行了多波束测深，海底地震仪广角地震，重新处理的遗迹和新的地震反射图像进行了调查。本文的总结和更新是以前的文章和其他数据。与余震区域边界并置的构造结构表明未来大地震的可能破裂长度。NE余震区域边界与俯冲的下部板块结构有关，而西南部带的上部板块保留了白令构造遗迹。将较坚硬的大陆架岩石与较弱的积聚的棱镜分隔开的较低到中等的斜坡过渡发生在先前被解释为地震图像中的逆冲断层的断层断裂带上。伸展断层的破坏带通常为1公里宽，通常为21°。八字形形成从板块界面到海底的滑动路径，比前棱柱下方的3–4°浸入板块界面要短得多。相关的海底通风口结构指示深处的流体超压。倾斜的断层倾角及其坚硬的悬挂壁比起每单位滑动增加的棱柱形的棱镜，海底隆起更大，从而使其成为有效的海啸发生器。整个阿拉斯加海沟都分布有逆止断裂扩展区（BSFZ）。在前棱柱下方，活动的弯曲断层增加了板块界面的褶皱度，通常在重新处理的旧数据和新地震数据中可以成像出千米高浮雕。1946年的Unimak大地震（M8.6）震中位于BSFZ附近。