There has been a ... ahem ... healthy discussion of Yellowstone's current earthquake swarm on Eruptions as of late. We've now reached ~1,500 measurable earthquakes over the last 11 days. The latest reports of the continuation of the swarm isn't going to make anyone happy, but still, there are no signs that (a) this is out of the ordinary and (b) indicates magma making its way to the surface. In fact, if you plot the earthquakes since the 22nd of January, the depth appears to getting, well, deeper:
This plot shows the earthquakes listed on the USGS earthquake page since January 22 (oldest to left, youngest to right) plotted against depth. If anything, the earthquakes seem to be becoming more restricted in their depth around 10-10.5 km and definitely not heading upwards. This is not to say that they won't, but with the evidence right now, the earthquakes seem to be pretty stably around 10-11 km depth. That, to me, seems to back up the USGS/YVO assertion of a tectonic origin - faults at depth (more or less) - rather than magma/liquid moving towards eruption (combined with the fact that the earthquakes are staying approximately the same magnitude range ~ 1-3).
However, you never know with a system like Yellowstone - nothing can really be considered "unrelated" to the caldera and we don't have a lot of evidence of how large caldera systems might behave before an eruption. However, remember, Yellowstone is just a big caldera - and we have experienced other caldera-related eruptions like Katmai/Novarupta in 1912 and Chaiten in Chile in 2008 - we're definitely not working with no idea what to expect. We can also model the potential types of behavior of a caldera if it were headed to eruption to at least give us an idea of what might happen, seismically speaking, if an eruptive sequence was beginning.
This earthquake swarm is clearly fascinating and well worth our time and attention. However, delving into conspiracy theories and fear is definitely not the way to go. I'll try to stay on top of the unfolding events, so watch this space if anything changes!
Physical Science
Environment
Comments (73)
Thanks, Erik. Seems like most agree that Yellowstone could erupt, but it doesn't look like it right now given the data. I have been trying to say that we can enjoy the experience of keeping tabs on Yellowstone and any other caldera or volcano out there and learn from it. We can also be prepared for emergencies. The usual ones we know about and then maybe be aware of the forces that move terra firma which isn't so firma. Like I said, I live near volcanoes and faults and in a fire prone area. Things to think about and have some idea what I would do in any of these cases.
BTW, my computer didn't register the plot you posted. I'm not sure why, but it didn't. The number of quakes reminds me of Long Valley when it was going to town. I remember checking the quake map and there were over 1000 for a week there at one time. I don't remember the year, but it was in the mid '90s. I remember, too, all the hullaballoo it created because of the resurgent dome area. It is still 80cm higher than it was in the '70s.
Seems like both of the calderas have acted simularly in recent times though Yellowstone is more active.
Let's keep watching and waiting for the next event and hope it doesn't do any harm to anybody.
Posted by: Diane | January 28, 2010 10:15 PM