In this paper, we investigate the sources for Palu Bay tsunamis, which occurred in September 2018 after a M w 7.5 earthquake struck on a strike-slip fault. Previous land-based field studies have identified numerous coastal landslides as possible sources for tsunami generation. Here, we present new post-earthquake bathymetry survey data in the bay. We compare the new very detailed nearshore bathymetry with the pre-earthquake data so as to quantify the magnitudes and configurations of coastal landslides and the characteristics of landslide-generated waves. We perform numerical simulations of tsunami propagation, isolating the coastal landslides as the only sources. The results show that, although the landslide-generated waves characteristically have shorter periods than the observed tsunami waves, the combination of the waves is able to produce long waves comparable with those observed, due to the ringing effects of the trapped waves inside the bay. Therefore, we conclude that landslide-generated waves played a significant role in the tsunamis in Palu Bay. Nevertheless, it is likely that the tsunamis were caused by a combination of tectonic and landslide sources.

中文翻译：

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2018 年苏拉威西地震和海啸期间帕卢湾的沿海滑坡

在本文中，我们调查了 2018 年 9 月发生在走滑断层上的 Mw 7.5 地震后发生的帕卢湾海啸的来源。以前的陆基实地研究已经确定了许多沿海滑坡可能是海啸产生的来源。在这里，我们展示了海湾中新的震后水深测量数据。我们将新的非常详细的近岸水深测量与震前数据进行比较，以量化沿海滑坡的大小和配置以及滑坡产生的波浪的特征。我们对海啸传播进行数值模拟，将沿海滑坡作为唯一来源。结果表明，虽然滑坡产生的波浪具有比观测到的海啸波浪更短的周期，由于海湾内被困波浪的振铃效应，波浪的组合能够产生与观察到的波浪相当的长波。因此，我们得出结论，滑坡产生的波浪在帕卢湾的海啸中发挥了重要作用。尽管如此，海啸很可能是由构造和滑坡源共同引起的。