Evaluating the role of eruptive processes in the source of the 2018 Anak Krakatau tsunami
Abstract
Volcanically generated tsunamis may involve poorly-predictable and complex combinations of explosive-eruption and mass-transport processes. Difficulties in forecasting these processes, along with the potential for extreme near-field wave heights, present a major challenge for mitigating volcanic-tsunami hazards. The lateral-collapse generated tsunami at Anak Krakatau, Indonesia, in December 2018, highlights the potentially devastating impacts of such events. Accurate reconstruction of tsunamis such as those at Anak Krakatau can help improve our understanding of source mechanisms and precursory signals, and is important both for developing monitoring and mitigation approaches, and for testing and improving numerical tsunami models. Here, we evaluate the role that eruptive processes played in the source mechanism of the tsunami. We assess whether changes in eruptive activity preceded the collapse, and may therefore be implicated in driving the instability, or if the changes in eruption behaviour that followed the event were simply a consequence of unloading of the shallow magma plumbing system. This is important for assessing whether precursory monitoring signals may be identifiable in such events, as well as for constraining tsunami source parameters. To address this, we combine sedimentological and petrographic analyses of pre- and post-event products of Anak Krakatau (post-collapse samples collected in 2019; and pre-collapse samples from 2017 and earlier stages in the development of Anak Krakatau) with remote sensing and other monitoring datasets, to reconstruct magmatic processes spanning the collapse. We also present a longer-term perspective on the setting and growth history of Anak Krakatau, evaluating how this played a role in the magnitude and geometry of the lateral collapse. Finally, we draw on these results to consider the outstanding challenges particular to forecasting volcanically-generated tsunamis.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMNH31A..02W
- Keywords:
-
- 4315 Monitoring;
- forecasting;
- prediction;
- NATURAL HAZARDS;
- 4333 Disaster risk analysis and assessment;
- NATURAL HAZARDS;
- 4341 Early warning systems;
- NATURAL HAZARDS;
- 4564 Tsunamis and storm surges;
- OCEANOGRAPHY: PHYSICAL