NEESR-SG: Physical modeling of 3D Tsunami Evolution Using a Landslide Tsunami Generator

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

Tsunamis can be generated directly by seismic impact. However, in some seismic events tsunamis have been observed to be triggered by the massive failure of the sea floor in the form of giant submarine landslides. According to the National Geophysical Data Center and World Data Center for Solid Earth Geophysics as well as Intergovernmental Oceanographic Commission, in the Pacific Ocean alone, 65 tsunami events attributed to submarine landslide caused a total number of 14,661 deaths. Our ultimate long-term goal is to develop a fundamental understanding of the mechanism of tsunamigenic landslides and subsequent tsunami generation, propagation, and run-up, which would allow for improved assessment and possible mitigation of the landslide and tsunami hazard. Unfortunately, the field data from real world observations are limited to very few cases, while the most important part of this data related to the tsunami generation stage is almost completely missing. The goal of the proposed research is to compensate for this lack of data by the physical modeling of 3-dimensional tsunami evolution using a novel landslide tsunami generator which will complement the existing NEES tsunami facilities. Towards this goal, the following subset of objectives will be achieved in the proposed research: Objective 1. Model Similitude: The governing model similitude, defining the design parameters for the proposed landslide tsunami generator, will be determined using dimensional analysis. Objective 2. A Novel Landslide Tsunami Generator: The proposed novel computer controlled pneumatic landslide acceleration mechanism, will enable individual control of the dynamic landslide parameters such as landslide location, geometry and acceleration. Objective 3. Landslide Parameters: To design of the experimental program we propose to determine the geometries and velocities of tsunamigenic landslides from the case histories. However, in order to cover the whole range of possible parameter combinations we are planning to use the novel analytical and numerical models of the shear-band propagation mechanisms of tsunamigenic landslides. Objective 4. Experimental Program: In the proposed experiments we shall measure the characteristics of the subaqueous landslide motion and the near-field tsunami generation, propagation and run-up in three dimensions. In addition the resulting landslide deposits will be mapped and their thickness recorded. Objective 5. Validation of the Proposed Mechanisms: The measured landslide and tsunami characteristics will be compared to the existing real world observations providing a validation for physical, analytical and numerical models used in this research. This will justify the use of these models in the development of fundamental understanding of the coupled landslide and tsunami mechanisms and allow us to develop recommendations for the future experimental and theoretical research. Expected Intellectual Merit of the Research: The proposed research will advance knowledge and understanding of landslide generated tsunamis . one of the most devastating natural hazards. Originality of the proposed work is based on its interdisciplinary nature, which combines experimental and theoretical Fluid, Soil and Fracture Mechanics approaches. The project is a joint effort between three Georgia Tech faculty members who combine expertise in fluid mechanics, physical modeling and tsunami hazards, soil mechanics and geotechnical engineering, rock and fracture mechanics. Expected Broader Impact of the Research: Understanding of landslide and tsunami mechanisms has broad implications not only to engineering but also to human endeavors. It will enhance both assessment and mitigation of tsunami and landslide hazards. The novel landslide generator developed in this research will complement existing NEES tsunami facilities both in the present and future studies. The funds provided from this proposal will be used to educate and support two graduate students. The results of this research will be incorporated into existing undergraduate and graduate level courses, and a new graduate course on Natural Hazards will be jointly developed by PIs. The results will be disseminated to a broad scientific and engineering audience through publications in high-impact professional journals and via presentations at national and international meetings. K12 audience will be reached by popular lectures and Internet postings emphasizing the important role of Civil Engineering profession in mitigation of natural hazards.