The heart of Yellowstone National Park is filled with pine forests, the huge cold-waters of Yellowstone Lake, scattered open meadows, dotted with wild bison, elk, and others, with rising steam from famous features, such as Grand Prismatic Hot Spring. So, where is this super volcano we’ve been hearing about? And maybe more importantly, when is it going to erupt? Let’s tackle these questions by first looking into the elements that make Yellowstone a super volcano. Then, let’s talk about the best guided Yellowstone experience with Big Sky Adventures & Tours, so you can immerse yourself in everything Yellowstone.
Geologists describe a super volcano as an eruption of magnitude of 8 or more on the Volcano Explosivity Index (VEI). It is an explosive, cataclysmic blast from an underlying magma pool lodged in the mantel, which erupts more than 240 cubic miles of material. In other words, it’s a really big volcano. The underlying magma chamber, also known as a hot spot, is responsible for the energy of the volcano. The bigger the hot spot, the bigger the volcano. The hot spot under Yellowstone is one of the largest, out of more than 30 hot spots around the world. And it is the largest hot spot located in the middle of a continent -- as most are under oceans (think of Hawaii). We’re talking about a magma chamber, in the mantel, stretching 5-17km (3-10 miles) below the surface. It is actually 2 magma chambers. The upper one is approximately 45 miles long and 25 miles wide, comprised of rhyolite (high silica concentration), which is mostly solid with approximately 5-15% melt (that's what creates Yellowstone's mud pots). The deeper chamber, composed of basalt (low silica), is 20-50km (12-30 miles) beneath the surface and is about 4.5 times the size of the upper chamber.
In Yellowstone, volcanic activity explodes through cracks in the overlaying crust and blasts out gases, ash, and magma. As more material is emitted, the weight of the crust sinks down to form a caldera. These volcanic explosions have occurred regularly over the past 16.5 million years. The calderas have been mapped from Yellowstone, through Idaho and Nevada, as the North American plate has moved over the hot spot, while the hot spot remains in place. There have been 3 of these caldera forming eruptions in what is now Yellowstone Park, dating to 2.1 million years ago and occurring approximately in 600,000 thousand-year increments.
Does that mean Yellowstone could blow any day now? Well, not likely, according to the Yellowstone Volcano Observatory (YVO). YVO is a partnership between the USGS, YNP, University of Utah, University of Wyoming, UNAVCO, MT Bureau of Mines and Geology, Idaho Geological Survey, and WY State Geological Survey. These scientists monitor Yellowstone for signs of volcanic activity, and there is no evidence that a catastrophic eruption is imminent. In fact, a Yellowstone eruption is unlikely to occur in the next few centuries. However, it is the primary energy for more than 10,000 geysers, hot springs, mud pots, and fumaroles, collectively known as thermal features.
So back to the question of: Where is the Yellowstone volcano? When you’re in Yellowstone National Park, you’re probably in the middle of the volcano, on top of it's crust. Hike with Big Sky Adventures & Tours: We walk through geyser basins and learn about geology, microbial ecosystems, and witness famous Old Faithful Geyser. Hike into Yellowstone's dense forests, along the Continental Divide Trail, to Shoshone Lake, or cross country ski along the banks of the Firehole and Madison Rivers. We are on the center of the volcano crater, or the center of the caldera, anyway. The oval shaped caldera is nearly 45 miles long and 30 miles wide. This is a land of fire and ice -- shaped by volcanos and glacial activity, which retreated 10,000 years ago. The soil was ground up, leaving gravel and rock, creating the perfect landscape for sprouting lodgepole pine forests.
One of our favorite hikes, where you can see the scale of the Yellowstone Super Volcano, is to the top of Mt. Washburn. At the northern edge of the caldera, you will witness the evidence of the Yellowstone Volcano and its plateaus spread out below, flanked by mountain ranges such as the Red Mountains, the Tetons, the Absaroka Beartooth Mountains, and the Madison and Gallatin Mountains to the north. What a wondrous sight!
The caldera rim is not so obvious, though, unless you are along the Firehole River. There you will see the sheer wall of rock along the water’s edge. Squint at it and imagine the seemingly molten magma wall flow before you. Travel upstream and you really are in the heart of the Yellowstone caldera and will believe that a volcano is alive and 'breathing.' Observe the valleys of steam around Fountain Paint Pots, watch geysers pulse hot water from mere inches to hundreds offeet in the air, and listen to the gurglings of underground thermal bubbling mud pots: understanding the connections, between the Yellowstone volcano and the thermal features, becomes clear. The rising steam from Old Faithful or Steamboat geysers and the other thousands of thermal features in Yellowstone say it all. We are standing on hot ground heated from below, providing energy for more geysers and hot springs than the rest of the world combined. Wow!
Thank you, Yellowstone Volcano
Cool Yellowstone summer evenings are turning into chilling, frosty fall nights. Aspens, willows, grasses and shrubs are displaying brilliant golds, reds, and oranges, and the bull elk are starting to move around. Elk have spent the summer in small herds of cows and calves grazing in alpine areas and hidden meadows. The cooler temperatures, along with recent snow in higher elevations, encourage many herds to find grazing areas lower down and often along river corridors. Elk, both females and males, called cows and bulls, are getting ready for the mating season we call the rut.
The rut occurs for about 6 weeks in September and October and is a very exciting time to view or listen to elk. Frequently we can hear sounds of cow elk squeaking warnings to their calves and coughing or barking as they communicate with one another.
One of my favorite sounds, and the sound that tells me fall is here, is the echo of a bull elk bugling. It’s a magical sound something like a cross between a loud high-pitched whistle and a guttural grunt. It’s like no other sound you’ve ever heard. However, to a cow elk it sounds like an eligible bachelor. Bull elk bugle to call in cows and to vocalize their power and dominance over other bulls that might be in the area. Sometimes we are lucky to witness a bull rounding up his group of cows and watch him work to keep his harem together. We may even catch a wolf watching and studying the herd too! The best time to witness this behavior is typically on an early morning hike, or at dusk along a river bank.
Join us on a hike to learn about other clues elk, and other wildlife, leave along the trail.
Days in Yellowstone are always inspiring, whether it’s the fall colors, beautiful skies, or elk bugles in the distance. The chill in the air tells me that winter snows are not far behind. Yippee!!
10 simple steps for being a guide in Yellowstone National Park: