KILAUEA VOLCANO UPDATE – Lava diversion?
I don’t update this “VOLCANOES IN THE NEWS” section often enough, and I should probably write something about the huge Barabunga volcanic eruption (over 1 km^3 erupted in past 5 months!), but 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 on Hawaii Island.......
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 last 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). 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 in late November, and took over three weeks to again threaten populated areas. USGS Hawaiian Volcano Observatory maps (below) show the now frozen "A" flow terminus and the new flow "B" that is now moving fitfully towards major structures west of old Pahoa town. The complex pyroduct system feeding the flow front appears to have become clogged. and is now feeding latral breakouts that are widening the flow instead of advancing the flow front.
USGS map showing the entire "27 June" flow.
USGS detailed map showing lateral breakouts on Flow "B"
If the eruption continues, and if Pele continues on her path to the northeast (following downslope drainage paths --- shown as blue lines on the regional map), Hwy 130 could 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, however, subject to natural disruption, 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. The supply rate to this flow is relatively low (<100,000 m^3/day) and may be insufficient to allow much further advance of the flow. If the eruption continues for many more years, however, or if lava supply rates increase, the threat to residential subdivisions below Hwy 130 will become more serious.
The artificial diversion of lava flows has been successfully used in Italy and Iceland to protect valuable properties, and is currently being discussed as an option to protect threatened property in Puna (a very controversial option!). To be considered as feasible, the terrain must be favorable, and there must be lesser value lands downslope towards which flows can be directed. Whether lava diversion will be seriously considered by Government agencies as appropriate to protect Puna properties in the future is yet to be seen. My thoughts about the subject were recently published in the Hawaii Tribune-Herald (http://hawaiitribune-herald.com/news/local-news/lava-diversion-can-it-work-should-it-be-considered). More information about lava diversion techniques is given in VOLCANOES – pp 438-442.