A Swarm of 200 Earthquakes Rocked the Ground Beneath Yellowstone's Volcano

Sounds scary, but scientists aren't worried.

The Norris Geyser Basin is the hottest geyser basin in the park and is located near the northwest edge of Yellowstone Caldera near Norris Junction and on the intersection of three major faults. The Norris-Mammoth Corridor is a fault that runs from Norris north through Mammoth to the Gardiner, Montana, area. The Hebgen Lake fault runs from northwest of West Yellowstone, Montana, to Norris. This fault experienced an earthquake in 1959 that measured 7.4 on the Richter scale. Norris Geyser Basin is so hot and dynamic because these two faults intersect with the ring fracture zone that resulted from the creation of the Yellowstone Caldera of 640,000 years ago. The tallest active geyser in the world is Steamboat Geyser and it is located in Norris Basin. Unlike the slightly smaller but much more famous Old Faithful Geyser located in Upper Geyser Basin, Steamboat has an erratic and lengthy timetable between major eruptions. During major eruptions, which may be separated by intervals of more than a year (the longest recorded span between major eruptions was 50 years), Steamboat erupts over 300 feet (90 m) into the air. Steamboat does not lie dormant between eruptions, instead displaying minor eruptions of approximately 40 feet (12 m). Norris Geyser Basin periodically undergoes a large-scale, basin-wide thermal disturbance lasting a few weeks. Water levels fluctuate, and temperatures, pH, colors, and eruptive patterns change throughout the basin. During a disturbance in 1985, Porkchop Geyser continually jetted steam and water; in 1989, the same geyser apparently clogged with silica and blew up, throwing rocks more than 200 feet (61 m). In 2003 a park ranger observed it bubbling heavily, the first such activity seen since 1991. Activity increased dramatically in mid-2003. Because of high ground temperatures and new features beside the trail much of Back Basin was closed until October. In 2004 the boardwalk was routed around the dangerous area and now leads behind Porkchop Geyser.en.wikipedia.org/wiki/GeothermalareasofYellowstone#Nor... en.wikipedia.org/wiki/Wikipedia:TextofCreativeCommons_...

Over the past few days, an earthquake swarm has shaken the supervolcano that lies beneath Yellowstone National Park. Between February 8 and February 18, the region experienced over 200 earthquakes, according to the United States Geological Survey. This might sound super scary, especially if you’ve read that this caldera could cause a volcanic winter when it erupts.

But since we’ve all experienced more than enough existential dread this month, let’s get one thing straight: The Yellowstone Caldera is not about to erupt, and it is not about to blanket the United States in lava and ash because of a seemingly large number of earthquakes.

For one thing, this earthquake swarm — a flurry of small quakes without one large initiating quake — is not a new phenomenon. In 2017, Yellowstone experienced a similar swarm, and experts say this swarm could just be lingering seismic activity from last year. According to the National Parks Service, earthquake swarms in Yellowstone are “common”: the largest happened in 1985 when over 3,000 earthquakes shook the northwest side of the park over the span of three months. It didn’t trigger any volcanic explosions then, and it will not now, say scientists.

Upper terraces of Mammoth Hot Springs, Yellowstone National Park, Wyoming. Hot water is the creative force of the terraces. Even though Mammoth Hot Springs lie north of the caldera ring-fracture system, a fault trending north from Norris Geyser Basin, 21 miles (34 km) away, may connect Mammoth Hot Springs to the hot water of that system. A system of small fissures carries water upward to create approximately 50 hot springs in the Mammoth Hot Springs area. Another necessary ingredient for terrace growth is the mineral calcium carbonate. Thick layers of sedimentary limestone, deposited millions of years ago by vast seas, lie beneath the Mammoth area. As ground water seeps slowly downward and laterally, it comes in contact with hot gases charged with carbon dioxide rising from the magma chamber. Some carbon dioxide is readily dissolved in the hot water to form a weak carbonic acid solution. This hot, acidic solution dissolves great quantities of limestone as it works up through the rock layers to the surface hot springs. Once exposed to the open air, some of the carbon dioxide escapes from solution. As this happens, limestone can no longer remain in solution. A solid mineral reforms and is deposited as the travertine that forms the terraces. Photo credit: Brocken Inaglory via Wikimedia Commons commons.wikimedia.org/wiki/File:UpperTerracesof_Mammoth...
Hot springs in Yellowstone lie north of the caldera system.

The last time this supervolcano erupted was over 70,000 years ago. In the time that modern scientists have been studying it, they’ve concluded that Yellowstone, even though it sits on top of a giant well of subterranean lava and experiences 1,000 to 3,000 earthquakes a year, has extremely low odds of erupting.

If there is going to be an eruption, geologists will be able to tell well in advance. USGS scientists say the current flurry of quakes is not a warning of an impending eruption.

Since the park experiences earthquakes so frequently, the fact that this swarm has yielded so many small quakes should not be worrisome. Add to that the fact that they really are tiny quakes, and our fears should be put to rest. The largest earthquake in this swarm has only registered a magnitude of 2.9, making it a very weak earthquake. To put it simply, you might not feel a 2.9 earthquake if you’re standing where it happened. Additionally, the quakes have been dozens of miles below the Earth’s surface.

So, for anyone who’s worried that the Yellowstone supervolcano will end life as we know it, there’s no need to worry. But if you were hoping it would put a quick end to our misery, take comfort in the fact that there’s probably another existential threat right around the corner.