Lengths and hazards from channel-fed lava flows on Mauna Loa, Hawai'i, determined from thermal and downslope modeling with FLOWGO

Using the FLOWGO thermo-rheological model we have determined cooling-limited lengths of channel-fed (i.e. 'a'(a) over bar) lava flows from Mauna Loa. We set up the program to run autonomously, starting lava flows from every 4th line and sample in a 30-m spatial-resolution SRTM DEM within regions corresponding to the NE and SW rift zones and the N flank of the volcano. We consider that each model run represents an effective effusion rate, which for an actual flow coincides with it reaching 90% of its total length. We ran the model at effective effusion rates ranging from 1 to 1,000 m(3) s(-1), and determined the cooling-limited channel length for each. Keeping in mind that most flows extend 1-2 km beyond the end of their well-developed channels and that our results are non-probabilistic in that they give all potential vent sites an equal likelihood to erupt, lava coverage results include the following: SW rift zone flows threaten almost all of Mauna Loa's SW flanks, even at effective effusion rates as low as 50 m(3) s(-1) (the average effective effusion rate for SW rift zone eruptions since 1843 is close to 400 m(3) s(-1)). N flank eruptions, although rare in the recent geologic record, have the potential to threaten much of the coastline S of Keauhou with effective effusion rates of 50-100 m(3) s(-1), and the coast near Anaeho'omalu if effective effusion rates are 400-500 m(3) s(-1) (the 1859 'a'(a) over bar flow reached this coast with an effective effusion rate of similar to 400 m(3) s(-1)). If the NE rift zone continues to be active only at elevations >2,500 m, in order for a channel-fed flow to reach Hilo the effective effusion rate needs to be >400 m(3) s(-1) (the 1984 flow by comparison, had an effective effusion rate of 200 m(3) s(-1)). Hilo could be threatened by NE rift zone channel-fed flows with lower effective effusion rates but only if they issue from vents at similar to 2,000 m or lower. Populated areas on Mauna Loa's SE flanks (e.g. Pahala), could be threatened by SW rift zone eruptions with effective effusion rates of similar to 100 m(3) s(-1).