Special Lecture on GeoEnvironmental Hazards – Ricardo Ramalho (Cardiff Univ)

“How the colossal eruption of Hunga Tonga Hunga Ha’apai triggered a global tsunami driven by a fast-moving atmospheric source”

Volcanoes can produce tsunamis by means of earthquakes, caldera and flank collapses, pyroclastic flows or underwater explosions. These mechanisms rarely displace enough water to trigger transoceanic tsunamis. Violent volcanic explosions, however, can cause global tsunamis by triggering acoustic-gravity waves that excite the atmosphere–ocean interface. The colossal eruption of the Hunga Tonga– Hunga Ha’apai volcano and ensuing tsunami is the first global volcano-triggered tsunami recorded by modern, worldwide dense instrumentation, thus providing a unique opportunity to investigate the role of air–water-coupling processes in tsunami generation and propagation. In this talk I will explore how a wealth of sea-level, atmospheric and satellite data from across the globe, along with numerical modelling, shows that the tsunami generated by the recent colossal eruption of the Hunga Tonga-Hunga Ha’apai volcano had a global reach and was driven by a constantly moving source in which the acoustic-gravity wave fronts radiating from the eruption transfer energy into the ocean via a resonance mechanism. This coupling mechanism has clear hazard implications, as it leads to unusually fast-travelling, far-reaching and enduring high tsunamis that pose a much larger threat to land masses that rise abruptly from the deep ocean, in a clear contrast to the slower earthquake-triggered tsunamis that amplify in shallow-water areas.

About Our Speaker —
Dr. Ricardo Ramalho is a Senior Lecturer in GeoEnvironmental Hazards at Cardiff University School of Earth and Environmental Sciences

Please join us a little early to meet Dr. Ramalho and enjoy some coffee, tea, and cookies!

10:30am – Welcome + Refreshments
11:00am – Talk

Questions? Contact Wahida Abed