nature.net
March 2007
New Tubes
By Robert Anderson
For anyone interested in geology, what could be more exciting than hiking inside a volcano, along tunnels that, until fairly recently, flowed with torrents of molten rock glowing yellow at about 2,000 degrees Fahrenheit? Around the world, there are dozens of volcanic regions where you can do just that. Mind you, the tunnels you hike in, called lava tubes, are not the main vents that conduct magma up from the bowels of the earth. Rather, they are channels that form beneath or on the slopes of some volcanoes when huge volumes of lava drain from the crater's reservoir.
The Big Island of Hawai'i is lava-tube central, an ideal place to explore old, emptied-out ones and to see new ones in action, making the Big Island bigger. On the Internet, start at Dave Bunnell's Virtual Lava Tube site. Scroll down to the diagram by Carlene Allred and click on any one of thirty-six features of this alien world.
Sometimes unusual life-forms populate the area around the tubes. Kent Bridges, a botanist at the University of Hawai'i at Manoa, has prepared a virtual tour of the rainforest plants that grow along the walkway into the Thurston Lava Tube, one of the most accessible caves on the Big Island. At Showcaves.com you can read about another of Hawai'i’s popular attractions, Kazumura Cave, the longest tube system in the world, with a surveyed length of 36.8 miles.
The Web site of the U.S. Geological Survey's Hawaiian Volcano Observatory has lots of good information on tubes still funneling lava to the sea. Click on “Kilauea” in the menu at the left, scroll down, and click on the link to a sketch that shows how the tubes relate to the main plumbing of “perhaps the world's most active volcano.” On the main menu, click on “Ocean Entry” (under “Volcanic Hazards”) and scroll down to select “Collapse of new land into the sea.” The section shows how lava builds new but remarkably unstable land.
For a look at how the tubes operate, as seen from above, check out the time-lapse volcano movies under “Kilauea,” on the main menu. All the movies are informative, but don't miss the one near the bottom of the list, titled “East Lae'apuki Lava Delta Collapse”: it records how, in just five hours, some thirty-four acres of newly created land vanished into the ocean.
In the continental United States, lava tubes occur throughout the volcanic regions of the west. At “Volcano World” learn about Ape Cave National Volcanic Monument, on the slope of Oregon's Mount St. Helens. At almost 2.5 miles in length, the cave is purportedly the longest intact stretch of lava tube in the continental U.S.
Outside the U.S., the Undara lava tubes (see Tunnels to A Wildlife underworld) in Queensland, Australia, are among the longest and they provide a perfect habitat for hordes of bats). The Web site of a travel company called EWP has photographs of lava tubes in the Azores.
Lava tubes are not even limited to earthly destinations. The Oregon L5 society has links to information and images of lunar and Martian examples. Such caves may offer human colonies the best protection from the harsh conditions on those distant worlds. Writing in Astrobiology Magazine, Penelope J. Boston, an astrobiologist at New Mexico Tech in Socorro, considers Life in a Lava Tube. Suddenly, that tube in Hawai'i is looking like a really great place to live.
Robert Anderson is a freelance science writer living in Los Angeles.
Copyright © Natural History Magazine, Inc., 2007