Hazard potential of volcanic flank collapses raised by new megatsunami evidence

Ricardo Dos Santos Ramalho, Gisela Winckler, José Madeira, George Helffrich, Ana Hipólito, Rui Quartau, Katherine Adena, Joerg Schaefer

Research output: Contribution to journalArticle (Academic Journal)peer-review

55 Citations (Scopus)
315 Downloads (Pure)

Abstract

Large-scale gravitational flank collapses of steep volcanic islands are hypothetically capable of triggering megatsu- namis with highly catastrophic effects. Yet, evidence for the generation and impact of collapse-triggered megatsu- namis and their high run-ups remains scarce or is highly controversial. Therefore, doubts remain on whether island flank failures truly generate enough volume flux to trigger giant tsunamis, leading to diverging opinions concerning the real hazard potential of such collapses. We show that one of the most prominent oceanic volcanoes on Earth— Fogo, in the Cape Verde Islands—catastrophically collapsed and triggered a megatsunami with devastating effects ~73,000 years ago. Our deductions are based on the recent discovery and cosmogenic 3He dating of tsunamigenic deposits found on nearby Santiago Island, which attest to the impact of this giant tsunami and document wave run-up heights exceeding 270 m. The evidence reported here implies that Fogo’s flank failure involved at least one fast and voluminous event that led to a giant tsunami, in contrast to what has been suggested before. Our observations therefore further demonstrate that flank collapses may indeed catastrophically happen and are capable of trigger- ing tsunamis of enormous height and energy, adding to their hazard potential.
Original languageEnglish
Article numbere1500456
Number of pages10
JournalScience Advances
Volume1
Issue number9
DOIs
Publication statusPublished - 2 Oct 2015

Keywords

  • volcanoes
  • islands
  • geology
  • flank collapses
  • megatsunami
  • tsunami
  • natural hazard
  • Fogo
  • Santiago
  • Cape Verde Islands

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