In this post I am going to discuss and show the details of an extremely peculiar rapid-fire earthquake swarm that just recently struck north of Green River in southwest Wyoming. This earthquake swarm was a rapid fire swarm, kind of like the ones seen from time to time near West Thumb Lake and Yellowstone Lake at Yellowstone, and is one of the craziest and coolest swarms I have ever had the chance to analyze. However a big difference is that this swarm, with magnitudes reaching around 3.0-3.2, contained many low frequency earthquakes. Sometimes the low frequency events were happening in such close proximity that they blended to create a type of low frequency tremor, which is what volcanic tremor is theorized to be made of. It is highly peculiar this type of earthquake swarm, with these magnitudes and this amount of energy, would even dare to strike in SW Wyoming. This was for sure a strange one and this post will detail as much as possible. Please click the title of this post or "read more" to continue, if you have not done so already.
If you would rather watch this as a video, please watch the video below. If you wish to skip to a part you want, please CLICK HERE to visit the video on my YouTube channel.
Around noon Mountain Time on February 22, 2019, an extremely energetic and peculiar earthquake swarm struck just to the northwest of Green River in the southwestern section of Wyoming. This location is an extremely strange location for an earthquake swarm, especially a rapid fire swarm such as this one. This earthquake swarm is for sure one of the craziest and coolest earthquake swarms I have ever analyzed (at least so far), well except for the 2008-2009 dike intrusion of Yellowstone Lake. In the image directly above you can see the location of the earthquake swarm in regards to 4 of the closest seismic stations.
As you will see within the plots below, this earthquake swarm contained mainly low frequency earthquakes with some of them occurring so fast that it sometimes blended to create a tremor-like event. This was a rapid fire swarm, much like the ones seen around West Thumb Lake and Yellowstone Lake from time to time (CLICK HERE). This also contained many low frequency events that appeared to have very similar characteristics to the possible magma resonance spotted during the 2008-2009 dike intrusion of Yellowstone Lake (CLICK HERE; scroll down to possible magma resonance). Also, please note that the depths of the earthquakes are likely to be extremely wrong. Now why is that?
I highly doubt the depths are correct. One of the events reportedly struck at -3.3km in depth, which would be approximately 10,826 feet above sea level. However if you check on Google Earth, the elevation where the epicenters are is about 6,400 feet above sea level. That means, if correct, these events transpired 4,400 feet above the surface of the earth? That is not possible. Plus, as you are about to see in a second, these events even traveled hundreds of miles showing up on seismic stations in Yellowstone Caldera and other areas as well so we know for a fact these events did strike underground somewhere. Sadly, I don’t think the depths will ever be accurately constrained since these were the wackiest low frequency events ever!
Also, there were many, many more of these strange low frequency earthquakes after the time period allotted in the description and plots below. It is entirely possible this strange swarm is still continuing, but in a diminished form. However since this happened this fast, it is likely this will happen again. I am currently contacting professionals to see what their take on this event was. I personally believe this was NOT tectonic, hydrothermal, or mine activity. That is due to the characteristics of the waveforms and the strength of the events compared to how fast they occurred. Now you will notice many of the events occurred in extremely rapid succession. In the plots below, it is almost impossible to view only one event due to how many are occurring. The energy of this swarm was impressive for the types of earthquakes that made up the swarm.
Overall, this was a good sized low frequency earthquake swarm with possibly some VLF events thrown in the mix. This swarm occurred on February 22, 2019 and info about this swarm is shown below:
-February 22, 2019 SW Wyoming swarm:
Start of swarm: 19:51UTC
End of swarm: 20:58UTC
Note: Although I have the time period of the swarm stated directly above, there were many more events after the main burst in seismicity. This swarm was extremely peculiar. In regards to its energy and how often the events transpire, it is similar to the rapid fire swarms seen around West Thumb Lake and Yellowstone Lake from time to time. Even though this earthquake swarm did contain some events with higher frequencies, most are still considered low frequency earthquakes. Also, some of the events that seem to be tremor may be multiple events occurring in such rapid succession you cannot tell them apart. The total estimated earthquake count below only counts the events within the time period stated above.
Total earthquake count (includes even the tiniest events): ~85 (if many of these were earthquakes, it is likely this number is somewhat higher for the time period above)
Reported count: 6 so far
Largest amplitude from closest station: 169,170 (GAWY-HHZ)
USGS EQ map of this swarm: CLICK HERE
Below I will first show 5 helicorder charts. 4 of them will be from the 4 closest seismic stations and the last one will be from MCID at Yellowstone which picked up these events quite well. The chance that any of these were occurring at or above the surface is basically 0 now. After that I will show some random images and then I will show the USGS event pages to 2 select events, along with their custom plots I made. Then I will detail much of the swarm from the time period stated above. I will not be able to show every single event, but I will show alot of them! Remember to always read chart labels first and any captions beneath any images.
Below I will detail alot of the low frequency earthquake swarm via the 3-plot images I like to generate. I will show them in slideshow format. The first slideshow contains 13 of these images, so does the 2nd slideshow. So, what do you think this swarm was caused by? Let me know!
An additional note, it seems there was an interesting increase in SO2 emissions basically in the same area as the swarm, just as the swarm was peaking/calming. Check it out (CLICK HERE to visit video on YouTube):
This blog page is solely for interesting earthquake swarms that occur in locations other than the ones I already have posted. Pretty much any earthquake swarm I am interested in, that cannot be placed on other pages, will be placed here. Please click the title of each post or "read more" to view each swarm.