Road across the flow
I’ve posted about my January visit to Pohoiki here, here, and here. The reason I was able to make that visit is because the county finally put a temporary road over one of the flows that cut off that part of the island.
One of the features of lava flows is that they don’t uniformly erase everything in their path. Sometimes they flow around areas. Sometimes they stop and a new flow emerges to one side. Sometimes a flow blocks one side of an area and a different flow blocks the other side.
The 2018 Kilauea eruption was no different in this regard. Some houses escaped destruction, but became inaccessible by road. Pohoiki was one of those places, until the new road was completed.
Things move at a leisurely pace in Hawaii and one might think the delay in building the road was due to this, but in this case, the county had good reason to wait. The simple reason is that they had to wait for the lava to cool down. It took several months for the lava to cool enough to make it practical to build a road over the flow. Even then it would not have been safe to cut through the flow and build the road at its former level.
How quickly the lava cools depends on many things including hot hot it was to begin with and how deep the flow is. It can take many months before the lava at the heart of a flow cools down enough to solidify and not present a danger.
For those interested in what happened during that 2018 eruption, the PBS show, NOVA, broadcast an episode titled ‘Kīlauea: Hawaiʻi on Fire.’ It’s about 50 minutes long and has a bit of a dramatic ‘will anyone survive’ tone in places, but I found it very informative. It might be available at https://www.pbs.org/wgbh/nova/, but if not you can see it here.