Invited review articleMega-tsunami conglomerates and flank collapses of ocean island volcanoes

- A review on marine conglomerates interpreted as evidence of mega-tsunamis cause by volcano flank collapse.
- A comprehensive picture of the methods and general characteristics of these tsunami conglomerates.
- Discussion on the use of tsunami conglomerates for constraining numerical models of flank collapses and tsunamis.
- Discussion on the possible links between volcano growth, flank instability, and climate.

Marine conglomerates at high elevation on the flanks of ocean islands are usually interpreted as evidence of mega-tsunamis generated by volcano flank collapses, although their origin is sometimes debated (elevated littorals vs. tsunami). In this review, we introduce case studies of well-documented examples of tsunami conglomerates in Hawaii (Pacific Ocean), the Canary and Cape Verde Islands (Atlantic Ocean), and Mauritius Island (Indian Ocean). Other less-documented marine conglomerates are also presented as tsunami candidates. Then, we build a comprehensive picture of the general characteristics of these conglomerates and the different methods that can be applied to date them. Different perspectives of research are proposed, especially on the use of tsunami conglomerates as proxies for better constraining numerical models of ocean island flank collapses and associated tsunamis. We also discuss the possible links between volcano growth, flank instability, and climate.