A Quick Caveat for Obsessive Yellowstone-Watchers
If you like apocalypse porn, you have probably been following the current earthquake swarm at Yellowstone. While there is no reason to believe that this is part of the lead-up to a giant caldera-forming eruption that will wipe out most of North America, or indeed to any eruption at all, there is also no reason to let that spoil your fun.
If you’re watching the recent earthquakes page, take the reported earthquake depths with an especially big piece of salt. Earthquake depth is difficult to accurately determine, especially with real-time automated processing techniques. Think about it: You’ve got seismometers scattered all over the surface, with lots of variation in x and y but no variation in z.
So even if earthquakes are listed at, say, 0.2 or 13 or 37 km, that doesn’t mean there is actually a “chimney” of seismic activity that penetrates the Yellowstone magma chamber or reaches up to the surface. According to USGS scientist Jacob Lowenstern, the most accurately located earthquakes so far have all been between 3 and 5 km depth.
You can also see more or less real-time data from Yellowstone’s continuous GPS network (though this is not a candidate for obsessive reloading – because most surface deformations of geological interest are smaller than errors in an instantaneous GPS measurement, the data is not useful until it’s been time-averaged). If there is something interesting (inflation or deflation) happening to Yellowstone’s magma chamber, or a gas-pressurized reservoir, we would expect to eventually see it as a slight change in surface topography.