Thurston Lava Tube, Volcano National Park
Thurston Lava Tube
Volcano National Park, Volcano, Big Island, Hawaii
While visiting a friend who lives in Volcano on the Big Island of Hawaii we took a late night cruise through the Thurston Lava Tube ... which was absolutely fascinating. Not the first tube for me to go down as I've been in some in Washington and New Mexico, but have to say I'm always impressed by them. I could picture placing a underground home in one someday. So what are lava tubes? They are natural conduits formed when an active low-viscosity lava flow develops a continuous hard crust which thickens and forms a roof above the still-flowing lava stream. It is a geological tube through which lava travels or once has travelled through beneath the surface of a lava flow that is expelled out by a volcano during an eruption. They are either actively draining lava from a source or are extinct meaning lava has cooled off and left a long cave-like tunnel. This is an extinct tube. As lava leaves the point of eruption in continuous extremely hot channels with cool surroundings that develop walls around them as the surrounding laval cools and the channel melts its way deeper - they often get deep enough to crust over forming an insulating tube that keeps the lava molten and acts as a conduit for the flowing lava. Pahoehoe flows are where lava is flowing in an unchanneled fanlike manner as it leaves the volcanic source taking a lava tube to lead back to the eruption point. These are areas of surface-moving lava that has cooled forming a smooth or rough ropy surface. Once the flow hardens, it starts to block its source, and only the subsurface lava is still hot enough to break out at a point creating a new source or underground channel known as a pahoehoe tube. Each tube often exhibits step marks called 'flow ledges' or 'flow lines' on the interior walls that show the various depths that the lava flowed. Most tubes have pahoehoe floors commonly covered with breakdown from the ceiling. Lavacicles (stalactites) or lava tube speleothems form in either splash, shark tooth, or tubular varieties as well as tubular lava helictites (drip stalagmites) are often formed in the tubes. Beads of lava that extrude from small holes that ran down the wall are known as 'runners'. Sometimes crystalization occurs in the tubes forming crusts of small crystals from mineral deposits in the flows. Lava tubes have been measured to be up to 14-15 meters wide and as deep as 1-15 meters below the surface - they can extend for miles in many instances. For example, the Mauna Loa tube runs over 30 miles from its eruption point. The Thurston Lava Tube is part of Hawaii's Volcano National Park and is easy to access within the park for a nice excursion it's definitely worth seeing. The Park was established in 1916 and remains an active Volcanic area. Active eruptive sites include the main caldera of Kîlauea and a more active but remote vent called Puʻu ʻÔʻô. Kîlauea and its Halemaʻumaʻu caldera are traditionally considered the sacred home of the volcano goddess Pele, and Hawaiians visited the crater to offer gifts to this Goddess. This tube is named after the Thurston family, the first western visitors to the site. They were English missionaries, William Ellis and American Asa Thurston in 1823. Their grandson, Lorrin A. Thurston, was the driving force to establish this park in 1916. There is an undeveloped stretch of this Lava tube that extends an additional 330 meters beyond the developed one show in these pictures and it dead-ends into the hillside. While blocked by a chain link fence to keep unwary visitors from entering, the easily traversed stretch is open to the public and accessible through a gate in the fence. Rating: 5 stars out of 5.