Part I: Tsunami field reconnaissance
On 26 December 2004, a great earthquake occurred off the North tip of Sumatra, Indonesia. A transoceanic tsunami was generated resulting in a tsunami death toll in excess of 200,000. The author covered most diverse coastlines impacted by the mega tsunami from the near to the far field encompassing Sumatra (Indonesia), Sri Lanka, The Maldives, Oman, Yemen, Somalia, The Comoros, Madagascar. A variety of standard tsunami field survey techniques were used. Numerous eyewitness interviews were recorded on video to estimate the number of waves, their height and period as well as the tsunami arrival time. In addition overland flow velocities were determined from eyewitness video recordings based on in-situ image rectification and Particle Image Velocimetry (PIV). The author also led tsunami survey teams in the immediate aftermath of the 17 July 2006 South Java tsunami and the 1 April 2007 Solomon Islands tsunami. The tsunami impact is compared against Hurricane Katrina's storm surge.
Part II: Landslide generated tsunami
Landslides may pose perceptible tsunami hazards to areas commonly regarded as immune. Tsunamis are commonly associated with submarine earthquakes. However more than 10% of all tsunamis are generated by landslides or landslide like volcano collapses with subaerial, partially submerged or submarine origins. In recorded history landslide generated tsunamis have attained local wave heights and runup heights of more than 100m and 500m, respectively, thereby locally exceeding maximum wave and runup heights of tectonic tsunamis by more than an order of magnitude. The coupling between the landslide motion and the generated tsunami waves is of critical importance given the characteristic trans-critical landslide versus tsunami velocity Froude numbers. Landslide generated tsunamis were investigated most recently in the three-dimensional tsunami basin at Oregon State University (OSU) based on the generalized Froude similarity. The landslide emplacement characteristics were controlled by means of a novel pneumatic landslide generator. Deformable landslides of subaerial and submarine origin were modeled with granular materials. State-of-the-art measurement techniques such as particle image velocimetry (PIV) were applied. Landslide generated tsunamis were investigated previously in a two-dimensional physical laboratory at the Swiss Federal Institute of Technology (ETH). The physical model results were compared to the giant rockslide generated tsunami which struck the shores of the Lituya Bay, Alaska, in 1958. Further the experimental results were used as a benchmark for numerical flow simulations.
Hermann Fritz is Assistant Professor at the School of Civil and Environmental Engineering, Georgia Institute of Technology.
His Research interests include:
Tsunamis; Hurricane storm surges; non-linear and breaking water waves; mass flows (subaerial and submarine landslides, avalanches, debris flows, turbidity currents, pyroclastic flows); oceanic volcano island collapses; hydraulic, coastal, marine and offshore structures; hydropower and wave energy; river engineering; sediment transport and morphologic processes; advanced whole field multi-dimensional measurement techniques (laser-based PIV, LSV and LIF); numerical simulations of multiphase flows; natural hazard mitigation and risk analysis