KILAUEA VOLCANO UPDATE – Lava diversion?
I don’t update this “VOLCANOES IN THE NEWS” section often enough; my last discussions were about the eruptions of Ontake and Indonesian volcanoes. However since 1) I live on Kilauea volcano, and 2) since Kilauea lava flows are very much in the news, I thought it opportune to share some perspectives about the current eruption……
The current Kilauea eruption began in 1983, but Pele (the Goddess in charge of Kilauea’s activity) has for the most part been sending lava flows down the sparsely populated south flank of the East Rift Zone into the sea, or burning rainforest in remote areas. Back in the 1980’s over 200 homes were destroyed by flowing pahoehoe, but that was a long time ago, and the ongoing eruption has attracted little attention. That began to change this summer, however, when a new eruptive vent opened on the northeast side of the rift zone, and narrow lava flows began to head eastward, toward more populated areas. The situation has become more critical over the past few months, as Pele directed her lavas at the small town of Pahoa (see USGS maps below for current situation). Fortunately, the first flow threatening Pahoa (FLOW "A") was narrow, was supplied by long conduit ("pyroduct") that was subject to heat loss, cooled, became more viscous, and eventually solidified at its distal end. Another flow (FLOW "B") broke out about 5 km upslope from Pahoa on December 1, and has taken over three weeks to again threaten populated areas . Here are USGS Hawaiian Volcano Observatory maps showing the now frozen "A" flow terminus and the new flow "B" that is now moving relentlessly towards a major shopping center west of old Pahoa town.
If the eruption continues, and if Pele continues on her path to the northeast (following downslope drainage paths --- shown as blue lines on the map), Hwy 130 will be crossed and the much more densely populated areas downslope from Pahoa (over 1,000 homes) could eventually be threatened. The lava conduits (“pyroducts”) presently supplying the flow front are subject to natural disruption upslope, however, which could cut off the immediate advance of the flow. The source vent location could change, the eruption could stop, flow directions could change in response to minor terrain obstructions, and populated areas may never be directly threatened. If the eruption continues for many more months or years, however, the threat to residential subdivisions is serious.
The artificial diversion of lava flows has been successfully used in Italy and Iceland to protect valuable properties. To be considered as feasible, the terrain must be favorable, and there must be lesser value lands downslope towards which flows can be directed. Economic, political, and cultural conditions must be evaluated, and the decision to “mess with Mother Nature” will always be controversial. Whether lava diversion will be seriously considered by Government agencies as an appropriate option to protect Puna properties in the future is yet to be seen…… Information about lava diversion techniques is given in VOLCANOES – pp 438-442.