Ramtin Sabeti (1) and Mohammad Heidarzadeh (2) European Geosciences Union General Assembly 2019, (07-12 April)- Vienna- Austria Poster No: EGU2019-16004 Preliminary results of the experimental study on the amplification of tectonic tsunami coastal wave heights due to landslide Ramtin Sabeti (1) and Mohammad Heidarzadeh (2) (1) Civil Engineering PhD student, Brunel University London, London, UK (ramtin.sabeti@brunel.ac.uk) (2) Department of Civil and Environmental Engineering, Brunel University London, London, UK (mohammad.heidarzadeh@brunel.ac.uk) Introduction Tsunami also known as a seismic sea wave is a series of ocean waves capable of generating surges of water reaching heights of over 30 m at the coastal areas. While most tsunamis are generated by submarine earthquakes, they may also be caused by landslide (Watts et al., 2005; Heidarzadeh and Satake, 2015). They may even be launched by the impact of a large meteorite plunging into an ocean, as they frequently were in Earth’s ancient past (Wünnemann and Weiss, 2015). Several factors contribute to the formation of submarine landslides the most common are earthquakes but others includes wave loading, human impact loading, and rainfall (Masson, 2006). The purpose of this work is to explore the characteristics of tsunamis from combined earthquake-landslide sources. Such events have been previously reported in Papua New Guinea in 1998 (Synolakis et al., 2002) and Kaikoura in 2016 (Heidarzadeh et al., 2019). We conduct experiments on various combinations of combined earthquake-landslide sources. Results and discussions The designed experiments feature two wave gauges for measuring the wave characteristics. Therefore, there are two graphs (amplitude over time) for every experiment. Amplitude-1 and Amplitude-2 (Figure 4) represent the data obtained by wave gauge-1 and wave gauge-2, according to this graph, the highest increase occurs in experiment 15 and is recorded by wave gauge-1. An increase of more than 60% is logged for this experiment between all 24 dual wave experiments. Figure 2 shows wave amplitude over time for the waves generated by landslide and earthquake while Figure 3 illustrated the landslide individually. Figure 5 depicts the percentage of increase in the maximum amplitude leading to the amplitude peak, based on four amplitudes (0.637, 0.780, 0.915 and 1.06 second) and as measured by wave gauge-1 and wave gauge-2. According to Figure 5 the maximum amplitudes recorded by wave gauge-1 however, in general, gauge-2 has higher measurements than does wave gauge-1. In all of the experiments, the maximum values are recorded at the wave period of 0.915 s. The high velocity of the wave maker generating the earthquake waves cannot be a crucial factor because the wave period of 0.637 second, which has the highest velocity, does not yield the highest rate for maximum amplitude. Combined wave Fig. 2 Only-landslide wave Method The experiments were set up in a 5 m long, 0.3 m wide and 0.47 m deep wave tank at Brunel University London. The experimental system entailed an acrylic slope, where the landslide took place, which could be altered to two different angles to alter the steepness (Figure 1). At the other end of the flume there was a paddle which is connected to a gearbox to generate regular waves as representative of earthquake wave. In addition, a permeable slope, acting as a damper, was situated at the other end of the flume with the aim of decreasing the impact of reflected waves on the experimental outcomes. The distance between the slope and gearbox was kept at 3.0 m (Figure 1). Two wave gauges were set up to measure the waves’ characteristic (amplitude and periods) produced by the landslide and the paddle wave (representative of earthquake waves). The paddle waves had a period of 0.6 -1.1 s (Figure 5). The two gauges help in determining the full wave environment as well as apprehend these waves’ interaction on each other. Dimensions of the sliding mass were 24 cm × 8 cm × 15 cm. The mass was manually driven down slope using a cable. Fig. 3 Conclusions Experiments were carried out to determine the characteristics of tsunamis from combined earthquake-landslide sources. Overall this research shows the amplitude of waves can reach significantly higher values if landslide and earthquake waves interact, causing increased energy for generating new waves without cancelling each other. A maximum increase of 60% was observed in our experiments. Fig. 4 Fig. 1 Reference Heidarzadeh, M. and Satake, K. (2015). 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