A time-lapse video showing lava engulfing a car on Hawaii’s Big Island a few days ago
The images are incredible. Hissing lava heedlessly crossing roads, gardens, engulfing cars and setting homes on fire. All the result of a major and deadly eruption of the Kilauea volcano on Hawaii’s Big Island. It all began on May 1 when small cracks appeared on the volcano on May 1. A towering plume of pink smoke followed and then a magnitude 6.9 earthquake. Now a dozen fissures have opened up as chunky lava flows bulldoze through the community of Leilani Estates.
We feel powerless watching the lava flows have their way with human property and boundaries. Nature is so utterly uncaring, but how can you get angry? There’s no ill intent or will to destroy. It’s just Earth being Earth, terrible as the consequences might be.
Hawaii and in particular, the Big Island, sits atop a volcanic hotspot, a narrow stream of hot mantle (made of magma or melted rock) that rises from the boundary between the planet’s molten core and the mantle, a thick layer of semi-plastic rock deep beneath the crust. Hawaii is located on a large plate of rock that floats atop the mantle called the Pacific Plate. As it moves to the west, magma rising from the hotspot punches through the plate, pouring out flow after flow of lava that cools and solidifies, forming a new island in the Hawaiian Island chain. That’s why Hawaii is a west-to-east succession of islands. Each was built while on the move over the magma plume.
Hawaiian volcanoes aren’t the tall, explosive type but rather “shield volcanoes,” named for the convex but flattened shape of a warrior’s shield. They ooze highly fluid lavas of molten rock that flow like rivers in slow motion, covering everything in their path. Magma is the name given to molten rock stored in Earth’s crust; lava is magma that erupts at the surface. Temperatures of most magmas and lavas are between 1,300° F to 2,400° F (700 °C to 1300 °C), hot enough to melt copper and gold but not quite steel.
You might wonder about the source of heat that heats the Earth that melts the rock that causes all these troubles for crust-dwellers. There are three we know of. The primary is the residual heat left over from the formation of the Earth 4.6 billion years ago. Called primordial heat, it was generated when small bodies crashed and ultimately stuck together through gravity to form the early Earth. The energy released in those impacts heated materials to around 18,000° F (10,000° C) and remains with us today, locked in the deep mantle and core 4,000 miles (6,400 km) beneath our toes.
A second is the flow of heavy, iron-rich material toward the core. That releases an additional ~3,000° F of heating. Then there’s the heat of radioactive decay from radioactive rocks within the crust and mantle. At this time, we don’t have a good handle yet on just how much it contributes to heating and melting of rock, but it’s a factor.
Earth’s not alone. Other planets, even moons, have molten cores and release lava … or at least once did before their cores cooled. Mars, the moon, Mercury Venus and Io (at Jupiter) comes to mind. Moons like Saturn’s Enceladus, Neptune’s Triton, and the dwarf planets Ceres and Pluto have volcanic activity based on liquid water or other fluids. Residual heat within or created by gravitational interactions with larger bodies, as in the case of Jupiter’s flexing and heating Io’s interior, keep these balls of rock lively.
** Special note: I participated in a podcast recently with my colleagues at the Duluth News Tribune about the pleasure of looking up and my new book. We had a lot of fun. The podcast just came out today — click here to listen.