Modeling of InSAR and GPS data suggests the 1996–2004 uplift was caused by an intrusion of magma about 14 km (8.7 miles) beneath Norris. When magma intrudes the

Modeling of InSAR and GPS data suggests the 1996–2004 uplift was caused by an intrusion of magma about 14 km (8.7 miles) beneath Norris. When magma intrudes the crust it cools, crystallizes, and releases gases that had been dissolved in the melt. Gas escape lowers pressure in the magma, causing the surface to subside. That's probably what was going on at Norris from 2005 to mid-2013. But rising gases can become trapped under an impermeable layer of rock, causing the kind of rapid uplift seen at Norris from late 2013 until the M 4.9 earthquake in March 2014. It seems likely the quake created microfractures that allowed gases to escape upward again, resulting in subsidence that ended in 2015. The third uplift episode from 2016 to 2018 suggests rising gases became trapped again, this time at a slightly shallower depth. Modeling indicates the source depth for the 2013–2014 uplift was about 3.2 km (2.0 miles) deep, compared to about 1.8 km (1.1 miles) for the 2016–2018 episode. Should you worry? In a word, no. Activity like this is probably common at Norris and, at other times, under the caldera, too. What's different is that we now have the tools to detect and model Yellowstone's ups and downs better than ever before. For the first time, we've been able to track an entire episode of magma intrusion, degassing, and gas ascent to the near surface. For those in the know, like you, that's awesome—not alarming.