Aug 15, 2018
School of Civil and Environmental Engineering
In this episode, host Dan Zehner interviews Georgia Tech tsunami researcher Hermann Fritz. Professor Fritz discusses his unusual academic focus and his current project creating a tsunami generating machine at the University of Oregon.
As a civil engineering graduate student at ETH Zurich, he was interested in studying flooding. Switzerland is highly exposed to flooding, landslides and other hazards related to climate. Fritz explains that as the permafrost line lowers, rocks and mountains become less stable.
As for studying landslide-generated waves, the trigger point for Fritz came from observing a human-generated landslide into Lake Lucerne. Although the resulting impulse wave did not match experimental simulations, Fritz was nevertheless fascinated by the work and spurred to study waves generated by landslides for his PhD.
He says a big challenge in tsunami research is that tsunamis are poorly documented, typically limited to observations of post-event occurrences like runups, scars and broken foliage.
Fritz provides a rundown of the events he’s studied, including the July 9, 1958, Lituya Bay tsunami in Alaska – one of the first tsunamis observed in modern times. The landslide was “like an elephant in a bathtub,” he says. Fritz had a chance to meet with survivors of the event, the Swensons, who happened to be on a boat that day and were able to provide a unique eye-witness account of the disaster. In that case, Fritz says, there was good agreement between the physical model and the event.
A more recent event he’s studied was the June 2017 landslide in Greenland. The giant rockslide caused a tsunami with a runup of more than 90 meters.
As a young professor at Georgia Tech, Fritz had the opportunity to study the aftermath of the December 26, 2004, Indian Ocean tsunami. He is grateful, he says, for being able to learn from a pioneering survey team at the site. He learned from the likes of USC Professor Costas Synolakis. The Indian Ocean tragedy proved to be a great learning experience for Fritz as an early career researcher. The basin-wide impact affected Indonesia, Sri Lanka and Sumatra. During the post event reconnaissance, the team analyzed video taken by eye witnesses, which enabled the researchers to calibrate flow velocities.
Fritz also had the opportunity to study impact of the 2011 earthquake and tsunami in Japan – which he had visited just 18 months prior to the event to observe the region’s extensive preparation for disaster: tsunami dykes, seawalls and vertical evacuation. Despite it all, 20,000 people perished. Fritz collected field data and analyzed video. It is one of the best documented tsunamis ever, he says.
Submarine volcanic eruptions. At Oregon State University’s Hinsdale Wave Research Lab, a NHERI facility, Fritz is utilizing the tsunami wave basin to build physical models of submarine volcanoes with what may be the world’s first volcanic tsunami generator. The models fill in gaps that are difficult to observe directly.
Fritz discusses the rare, submarine volcano generated tsunamis that have happened in the past, including the island of Santorini in Greece and, more recently, Krakatoa – which killed 35,000 people due to landslides and tsunami. In the Hinsdale lab, the largest such facility in the U.S., Fritz can conduct large-scale experiments in a wave tank the size of an Olympic swimming pool,
Not only are volcanic tsunamis rare, they are compounded by ash, pyroclastic surges, and other characteristics, which make them difficult to study. In the lab, he says, he can isolate the elements. He is isolating the vertical explosion, wave propagation, landslide generation, the runup, the caldera formation -- all phases of an underwater volcano. The study will answer questions like: what kind of waves do we get, and how do they compare with other types of landslide or earthquake generated waves?
Follow Professor Fritz on Twitter: @hermfritz