Noname manuscript No. (will be inserted by the editor) Advanced Tsunami Numerical Simulations of The Puerto Rico October 11, 1918 Mona Passage Tsunami Alberto M. L´ opez-Venegas · Juan Horrillo · Victor Hu´ erfano · Aurelio Mercado · Alyssa Pampell-Manis Received: date / Accepted: date Abstract The most recent tsunami observed along the coast of the island of Puerto Rico occurred on October 11, 1918 after a magnitude 7.2 earthquake was generated in the Mona Passage. The earthquake was responsible for triggering a tsunami that mostly affected the northwestern coast of the island of Puerto Rico. Runup values from a post-tsunami survey indicated the waves reached up to 6 meters. A con- troversy regarding the source of the tsunami has resulted in several numerical simulations involving either fault rupture or a submarine landslide as the most probable cause of the tsunami. Here we follow up on previous simulations of the tsunami from a submarine landslide source off the western coast of Puerto Rico as triggered by the earthquake. Im- provements from our previous study include: (1) a higher resolution bathymetry, (2) a 3D-2D coupled numerical model specifically developed for the tsunami event, (3) the use of the non-hydrostaticnumerical model NEOWAVE, featuring two-way nesting capabilities, and (4) a comprehensive en- ergy analysis to determine the time of full tsunami wave development. The three-dimensional Navier-Stokes model TSUNAMI3D for two fluids (water and landslide) is used to determine the initial wave characteristic generated by the submarine landslide. Employing NEOWAVE allows us to Alberto M. L ´ opez-Venegas Department of Geology University of Puerto Rico - Mayag¨uez Cam- pus, Mayag¨ uez, PR. Juan Horrillo Texas A&M University at Galveston, Galveston, TX. Victor Hu´ erfano Puerto Rico Seismic Network, University of Puerto Rico - Mayag¨uez Campus, Mayag¨ uez, PR. Aurelio Mercado Department of Marine Sciences University of Puerto Rico - Mayag¨uez Campus, Mayag¨ uez, PR Alyssa Pampell-Manis Texas A&M University at Galveston, Galveston, TX. solve for coastal inundation, wave propagation and detailed runup. Our results are in agreement with previous works in which a submarine landslide is favored as the most probable source of the tsunami, and the improvement in the resolu- tion of the bathymetry yield inundation of the coastal areas that compare well to values from a post-tsunamisurvey. Our unique energy analysis indicates that the majority of wave energy is isolated to the wave generation region, particularly at depth near the landslide, and once the initial wave prop- agates away from the generation region its energy begins to stabilize. Keywords 1918 Mona, tsunami, submarine landslide, Volume of Fluid, three dimensional model, non-hydrostatic model Received: date / Revised version: date Introduction The most recent tsunami affecting the island of Puerto Rico in the northeastern Caribbean occurred on October 11, 1918. The tsunami, which affected mostly the northwest coast of the island, was observed shortly after a M w 7.2 (Doser et al., 2005) earthquake originating somewhere in the Mona Pas- sage (Figure 1). A post-tsunami survey carried out by Reid and Taber (1919) reported runups ranging from 3 to 8 m along the northwest coast of Puerto Rico, approximately four million dollars in damage, and 110 casualties from the earth- quake destruction and 40 people drowned as a result of the tsunami. The first effort in modeling the October 11, 1918 tsunami came from Mercado and McCann (1998), who as- sumed an instantaneous co-seismic dislocation as the initial tsunami source. Although their fault model yielded overall good agreement, it was unable to reproduce the observed negative polarityof the first wave arrival and detailed runups. An alternative mechanism for this tsunami event is based on