Yellowstone Supervolcano – July 15, 2020
While we were in Wyoming last week, we had a chance to spend some time at Yellowstone National Park. As a geologist, I am fascinated by the alien-looking terrain of active volcanic landscapes. Yellowstone is particularly interesting because it is home to a supervolcano formed as a result of a “hotspot”. Typically, volcanoes occur at plate boundaries and take on a classic conical shape, like the Andes and Cascade volcanoes. A hotspot is a volcanic region fed by underlying mantle that is anomalously hot. Magma in the mantle rises into the crust but cannot break through. As a result, pressure starts to build in a large and growing “magma pool” until the crust can no longer contain the pressure and there is a massive eruption. A supervolcano’s volume of ejecta (deposits) is greater than 1,000 cubic kilometers and can cause widespread devastation.
Geologically speaking, Yellowstone’s activity is quite recent, with calderas (hollows that form in the landscape after a magma chamber empties out and destabilizes the rock above) formed 2.1 million, 1.3 million and 630,000 years ago. It was exciting to drive into the caldera and then explore all the hydrothermal features of the region, which are the visible expressions on the surface of the supervolcano below. In Yellowstone, there are many hot springs and geysers: the former are the most common features in the park. They have no constrictions, so heated water can rise, cool and sink freely. The latter (geysers) are hot springs with constrictions in their plumbing system. This restricted water flow builds pressure, flashing water to steam, and the steam then rises and pushes water upward, decreasing the pressure, causing an eruption of water and steam. The beautiful colors (e.g., reds and oranges) you see? They’re formed by microscopic lifeforms (such as Archaea, cyanobacteria, protozoa, etc.) This is just a taste of Yellowstone – more on this supervolcano, geyser activity and lifeforms in an upcoming Science Short!