MODELING THE EFFECTS OF TRANS-PACIFIC TSUNAMIS ON NU’U, HAWAI’I

Over the last few hundred years, Hawaii has been suspectable to multiple tsunamis from both Cascadia, Aleutians, as well as other Pacific-wide earthquake sources. Nu’u, Hawaii is a wildlife refuge located on the island of Maui, where multiple coral boulders deposited in the area are interpreted as having deposited in a high energy event, likely a tsunami, due to their size and depositional pattern. There is also a deposit of marine sediments in the Nu’u wetlands, about 100 meters inland from the shoreline, similarly interpreted as from the same tsunami(s).

Through modeling we are able to distinguish differences in the effects of these tsunami on Nu’u and the regional area to compare to the geologic data. In this project we use GeoClaw, a tsunami modeling program to simulate the tsunamis using data from past earthquakes. The Aleutian earthquake is thought to have occurred between 1425-1665 (Butler et al., 2014), while Cascadia happened in 1700 (Atwater et al., 2005). We also compared these earthquakes to the 1575 South Pacific (Moernaut et al., 2007) and 1420 Chile tsunami (Ruiz and Madariaga, 2018). By modeling the paths of these tsunamis, using simulated tide gauges to record tsunami wave heights around Maui, and calculating the maximum inundation of the tsunamis in Nu’u, we were able to see how each of the events differed. Our preliminary results show that Aleutian tsunamis had higher wave heights near Nu’u in comparison to Cascadia. Cascadia and Aleutians tsunamis had similar arrival times to Nu’u around 4-5 hours, and maximum wave heights occurred on average at about 6.5 hours. Modeling from additional earthquake sources is in progress.