Redoubt Volcano is a 3108 m tall stratocone located in Cook Inlet, Alaska that explosively erupts roughly every 20 years. The five eruptions since 1900 all share the common characteristic of being accompanied by multiple large to very large lahars (108 to 109 m3), as well as many that are smaller in magnitude (104 to 106 m3). About 35 km from the crater of Redoubt Volcano lies the Drift River Marine Terminal that, if inundated, has the potential to cause an oil spill comparable in size to the Exxon Valdez spill of 1989. Non-Newtonian lahar flows evolve as they move down valley as a result of their bulking and debulking processes. The aim of this project was to model the largest lahars from the three most recent eruptions of Redoubt to better predict the area of inundation during future eruptions. Using GIS and the lahar simulation program Laharz_py, inundation models were created and compared with the known mapped area of post-eruption inundation done by the USGS for the seven most extensively studied lahars spanning the three most recent eruptions (1966-68, 1989-90, and 2009). The input data for these simulations consisted of a ten-meter resolution DEM and estimates of glacial meltwater volume as a measure of initial lahar volume proposed by both Dorava and Meyer (1994) and Waythomas et al. (2013). To capture the specific characteristics of the Redoubt Volcano lahars, a retrospective manipulation of the calibration factors was performed, such as the starting coordinates of the lahars, using the previously mapped areas of inundation. It was found that lahar volumes of approximately 4–5 x 108 m3 were required in order for the lahar run-out to reach the Drift River Marine Terminal. Volumes of this size appear to be consistent with estimates by both Dorava and Meyer (1994) and Waythomas et al. (2013), with the exception that the mapped areas of inundation appear more channelized than the simulations. These modeling techniques can be used in order to aid in the prediction of the lahar inundation for future eruptions of Redoubt Volcano.
Iezzi, Alexandra, "Modeling Lahar Inundation with the Aid of Historic Flow Deposits at Redoubt Volcano, Cook Inlet, Alaska" (2015). Physics, Astronomy and Geophysics Honors Papers. 6.
The views expressed in this paper are solely those of the author.