Title: Physical Modeling of Tsunamis generated by Submarine Volcanic Eruptions
Abstract: Volcanic tsunamis are generated by various source mechanisms such as underwater eruptions, pyroclastic flows, landslides, caldera collapses and phreatomagmatic explosive eruptions as highlighted by the 2022 Tonga event and 2018 Anak Krakatau tsunamis. The 1883 Krakatau eruption in Indonesia caused more than 36,000 victims due to tsunami waves and pyroclastic flows in the Sunda Strait. The mechanism of tsunami generation by submarine volcanic eruption was isolated and a volcanic tsunami generator (VTG) designed and deployed in the tsunami wave basin (TWB). The volcanic tsunami experiments were performed in the O. H. Hinsdale Wave Research Laboratory at Oregon State University in Corvallis, Oregon. The wave maker is a novel pneumatic volcanic tsunami generator, which allows for controlled vertical acceleration. The instrumentation deployed inside the basin includes wave gauges, runup gauges and multiple purposed cameras such as PTZ, PIV and underwater cameras. A linear potentiometer (MLO-POT) is installed inside the VTG to record the vertical displacement during the wave generation process. The potentiometer and wave gauge data are analyzed to characterize the generation and propagation of surface waves in radial and angular directions. The tsunami wave maker’s vertical stroke motion generates leading elevation or positive N-waves. A concentric vertical spike is formed by superposition of the circular bore from the wave generator motion. The tsunami wave characteristics from the large-scale physical model are compared with existing wave theories and models. The attenuation rate of the leading wave exceeds the range predicted by the linear wave theory in scenarios with relatively large Froude numbers. The comparisons between wave energy and source energy show that at most 60% of the potential energy in the initial dome shaped water surface deformation is converted to the wave train and up to 40% to the leading wave. Empirical equations are derived to characterize and evaluate tsunami wave parameters like amplitudes and periods, which can help to improve current tsunami warning and mitigation systems with consideration of volcanic tsunami hazards. The experimental data serves as benchmark to validate and advance three-dimensional numerical volcanic tsunami prediction models.
Biography: Dr. Hermann Fritz is a professor of civil engineering at the Georgia Institute of Technology (Georgia Tech). He is an expert on tsunamis and coastal hazards, such as hurricane storm surges, landslides and submarine volcanic eruptions, as well as their mitigation and coastal protection. Dr. Fritz has led or participated in more than a dozen post-disaster reconnaissance campaigns encompassing tsunami, hurricane, landslide, and earthquake events. Tsunami Surveys: 2004 Indian Ocean (Indonesia, Sri Lanka, Maldives, Somalia, Madagascar, Oman, Yemen, Comoros), 2006 Java, 2007 Solomon Islands and Peru, 2009 Samoa, American Samoa, and Tonga, 2010 Solomon Islands, Haiti, Chile, and Mentawai Islands, 2011 Japan, 2012 El Salvador, 2013 Solomon Islands, 2014 and 2015 Chile, 2017 Greenland. Hurricane Surveys: 2005 Hurricane Katrina, 2007 Tropical Cyclone Gonu (Oman), 2008 Tropical Cyclone Nargis (Myanmar), 2013 Typhoon Haiyan (Philippines), 2015 Tropical Cyclone Pam (Vanuatu), 2017 Hurricane Nate. Dr. Fritz’s research centers on fluid dynamic aspects of natural hazards such as tsunamis, hurricane storm surges and landslides as well as their mitigation and coastal protection. Dr. Fritz obtained his Doctorate degree (Dr. sc. ETH Zurich) in 2002 from the Swiss Federal Institute of Technology in Zurich (Switzerland).
To join virtually: Zoom
Contact: fritz@gatech.edu
Website: https://ce.gatech.edu/directory/person/hermann-m-fritz
Recording: Zoom Recording (will be available within a week after the seminar)