On 22 December 2018, a devastating tsunami struck Sunda Strait, Indonesia without warning, leaving 437 dead and thousands injured along the western Java and southern Sumatra coastlines. Synthetic aperture radar and broadband seismic observations demonstrate that a small, <~0.2 km3 landslide on the southwestern flank of the actively erupting volcano Anak Krakatau generated the tsunami. The landslide did not produce strong short-period seismic waves; thus, precursory ground shaking did not provide a tsunami warning. The source of long-period ground motions during the landslide can be represented as a 12° upward-dipping single-force directed northeastward, with peak magnitude of ~6.1 × 1011 N and quasi-sinusoidal time duration of ~70 s. Rapid quantification of a landslide source process by long-period seismic wave inversions for moment-tensor and single-force parameterizations using regional seismic data available within ~8 min can provide a basis for future fast tsunami warnings, as is also the case for tsunami earthquakes.

中文翻译：

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2018年12月22日，阿纳克·克拉卡托火山爆发时侧翼坍塌引发的海啸。

2018年12月22日，一场毁灭性的海啸毫无预警地袭击了印度尼西亚的Sun他海峡，在爪哇岛西部和苏门答腊南部海岸线上造成437人死亡，数千人受伤。合成孔径雷达和宽带地震观测表明，在积极爆发的火山阿纳克·克拉卡托火山西南翼的一个小于0.2 km3的小滑坡引起了海啸。滑坡没有产生强烈的短时地震波。因此，先验地震动并没有提供海啸预警。滑坡期间的长周期地震动源可以表示为指向东北的12°向上倾斜的单力，其峰值约为〜6.1×1011 N，准正弦持续时间约为〜70 s。