Tsunamis from earthquakes of various magnitudes have affected Cascadia in the past. Simulations of Mw>7.5–9.2 earthquakes constrained by earthquake rupture physics and geodetic locking models show that Mw>8.5 events initiating in the middle segments of the subduction zone can create coastal tsunami amplitudes comparable to those from the largest expected event. The simulations reveal that the concave coastline geometry of the Pacific Northwest coastline focuses tsunami energy between latitudes 44°-45° in Oregon. The possible coastal tsunami amplitudes are largely insensitive to the choice of slip model for a given magnitude. These results are useful for identifying the most hazardous segments of the subduction zone and demonstrate that a worst-case rupture scenario does not uniquely yield the worst-case tsunami scenario at a given location.