Physical modeling of tsunamis generated by subaerial, partially submerged, and submarine landslides

ABSTRACT

In the present study, three different types of landslide-generated tsunamis (subaerial, partially submerged and submarine) were investigated through laboratory experiments that used 261 different experimental conditions. The results show that, for the near-field region, the subaerial landslide generated a higher leading wave, while the submarine landslide generated a higher second wave. However, frequency dispersion considerably influenced their propagation, with the leading wave decaying and the trailing waves being enhanced. The present study also revealed that the leading wave has higher values for wave celerity, period, and length than the second wave, regardless of landslide type. It was also shown that the celerity of the leading wave and second wave can be approximated by the solitary wave theory and third-order Stokes theory, respectively. Using the extensive experimental dataset obtained, predictive equations to estimate the maximum crest amplitudes generated by partially submerged and submarine landslides were also developed. A comparison with the experiments of previous researchers and field survey data from the 2018 Palu Tsunami indicated that these equations can estimate reasonably well the height of the generated tsunami. It was also shown that the relative mass and initial position of the landslide are influential nondimensional parameters to determine the tsunami amplitudes generated.

KEYWORDS:

• Tsunamis
• landslides
• physical model
• 2018 Palu Tsunami

Acknowledgments

The present work was supported by JSPS KAKENHI Grant Number JP19K15104 and JST, J-RAPID Grant Number JPMJJR1801. The research activities of the second author were supported by the JSPS KAKENHI Grant in-Aid for Research Fellows (JP20J14032). The work was performed as a part of activities of Research Institute of Sustainable Future Society, Waseda Research Institute for Science and Engineering, Waseda University. The authors would also like to kindly acknowledge the input of several anonymous reviewers, whose comments helped to greatly enhance the quality of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

¹ In Figure 4, the time when water surface elevates to 1.5 mm above the initial water surface at WG2 is defined to be 1.00 sec, and thus it is not relevant to the times shown in Figure 3.

² Thus, these results will not be shown in some of the subsequent figures, which indicate the results of a_t1 and a_c2.

³ Their experimental results are available on http://sharif.edu/~ataie/ImpWave/SubmarinExp

Additional information

Funding

This work was supported by the Japan Society for the Promotion of Science [JP19K15104]; Japan Science and Technology Agency [JPMJJR1801]; Japan Society for the Promotion of Science [JP20J14032].