Three different lavasheds were computed for the same hypothetical project site using three different values of the angular region parameter. Only the 90-degree lavashed is sufficiently general to permit outlining both paths all the way to Mauna Loa s summit. The 90-degree lavashed is the most general and probably includes more area than is useful for our purpose. Neither enters the hypothetical project site. The DEM we used includes the topographic expression of all flows except the 1984 flow, because the DEM is based on air photos taken in the 1970s.
All lava flows that inundate the project site enter from the lavashed.
Not all lava flows that begin within the lavashed will enter the project site. Such breakouts should be treated as separate flows that originate at the breach point. A lavashed is a reasonable means of using terrain to define the area from which lava flows can enter a project site. Lavashed maps with these warning lines can be used to estimate how much lead time is available to respond to a flank eruption that begins within the lavashed. For example, using figure 9 we can estimate that a flow produced by a vent that opened on the 9-hour warning line could enter the existing prison project site 9 hours later.