Thus far, we have only discussed surface waves generated by wind blowing over a body of water (i.e., wind waves). This chapter will address the forces exerted upon overland structures subject to tsunami inundation based on Energy Grade Line Analysis (EGLA) first introduced in ASCE 7-16. Tsunamis are surface gravity waves produced by the sudden displacement of a large volume of water. Common triggering sources induce undersea earthquakes (e.g., 2004 Indian Ocean tsunami) and volcanic eruptions (e.g., 2021–22 Hunga Tonga–Hunga Ha’apai tsunami). Landslides that deposit large quantities of rock and soil into the water can also generate tsunami waves propagating outwards from the source of impact (e.g., 1958 Lituya Bay tsunami). When considering geologic timescales, asteroid impacts were responsible for producing some of the largest tsunamis ever to occur on earth (e.g., the Chicxulub impactor 66 million years ago). Unlike wind waves with periods on the order of seconds, tsunamis can have wavelengths exceeding hundreds of kilometers and periods of over an hour.