On the effects of landslide deformability and initial submergence on landslide-generated waves

Abstract

This paper represents a numerical study on the effects of landslide initial submergence and its geotechnical and rheological properties on the characteristics of landslide-generated waves (LGWs) and landslide deformation. A number of 117 numerical experiments are performed using a two-layer Coulomb Mixture Flow (2LCMFlow) model on a real-sized numerical flume as a simplified cross section of the Maku dam reservoir, located in the Northwest of Iran. Three different initial locations are considered for landslide representing a subaerial (SAL), a semi-submerged (SSL), and a submarine (SML) landslide. Based on the numerical results, the majority of SMLs and in some cases SSLs generate tsunami waves with a larger wave trough than the wave crest. The maximum negative wave amplitudes of LGWs caused by SMLs (SMLGWs) can be up to 55% larger than that for SALs. LGWs caused by SALs (SALGWs) commonly have a higher wave crest than the wave trough. In 70% of cases, the maximum wave crests of SALGWs are larger than that for LGWs caused by SSLs (SSLGWs) and SMLGWs. While, in the rest 30% of simulations, the maximum SSLGW crests are up to 60% larger than SALGWs. Due to the landslide inter-phase interactions in combination with its basal and internal friction resistances, only 10–40% of the SAL initial mass contributes in LGW generation process. Energy transfer from landslide into water is about 0.5–7.5% for SMLs, 6–17.2% for SSLs, and 5–15% for SALs. The final deposit of SMLs generally has a short and thick profile while SALs and SSLs elongate more and travel longer distances. Finally, a Coulomb mixture product parameter, PCM, is defined to relate the maximum LGW heights to the considered landslide properties.