For about 12 hours or so on July 23, 2019, a moderate swarm broke out to the east of the Lower Geyser Basin area at Yellowstone National Park. In this post I will show the usual seismic data and audio pertaining to this earthquake swarm. I will also show this swarm did not occur on any particular fault structure, so it is likely this was a fluid-driven earthquake swarm (as are many swarms at Yellowstone due to the large hydrothermal system underlying the surface). Please click the title of this post or "read more" to continue...
In the image above, the main swarm epicenter is circled in black. The 4 closest seismic stations are also labeled above. Note it occurred just to the east-northeast of the Lower Geyser Basin, which resides just north of the Upper Geyser Basin and north-northwest of the Mallard Lake resurgent dome.
As seen in the image below, this earthquake swarm did not strike on any locatable fault structures and the depth and style of earthquake activity seems to point to it being "fluid-driven". That being said, swarms account for more than 50% of earthquake activity at Yellowstone National Park. However, a large portion of those swarms are likely connected to hydrothermal fluids and, less likely, magma itself. If this were an intrusion of magma, we should have seen this last must longer, carry much higher magnitudes, and occur in conjunction with swelling of the ground (uplift). That is not what we see with this swarm. Regardless, let's take a look at some of the data.
If you wish to keep tabs on the earthquakes reported for this swarm, please do so by clicking the USGS EQ map button above. There is also another button above which will show you all seismic stations within Yellowstone National Park.
July 23, 2019 swarm:
Start of swarm: 06:00UTC
End of swarm: 19:21UTC (Total of 13 hours and 21 minutes.)
Info: Although this earthquake swarm did carry some energy, this cannot be characterized as a rapid-fire swarm. However, that being said, it still seems likely this swarm was caused by magmatically-derived fluids (likely hydrothermal fluids originating from very near the magma chamber).
Total earthquake count (includes even the tiniest, unreported events): ~150 events of all sizes (there could be more; likely only 50 at the max were locatable, seeing many were extremely tiny)
Reported count: 36 so far (more may be reported soon)
Largest reported earthquake of this swarm: M2.9 at 7.9km in depth
Largest amplitude: ~211,000 (PB_B207_--_EHZ), ~32,800 (WY_YML_01_EHZ)
Severity: Moderate one-day swarm
Depth of swarm area: So far, the deepest event in the swarm was reportedly a M0.4 at 12.7km in depth to the SE. The shallowest event reported was a M1.2 at 2.0km in depth.
DISCLAIMER: If you wish to see which earthquakes in the plots below were reported, simply go to one of the buttons I provided somewhere above that shows you the USGS earthquake map for Yellowstone during this time period. Earthquakes are reported in UTC and the times on the plots are in UTC as well. Plots will also be posted in order from first to last. Also, I do not detail every single event of the swarm in the plots below. However, I do try to show most of them.
Be wary! There are a total of 83 images total for the two slideshows below (not counting the helicorder slideshow). I will first show the helicorder plot slideshow first, then I will post the 2 separate slideshows containing the actual seismic plots.
The following is the seismic audio to this earthquake swarm, taken from B207 which was the closest station to these events. All seismic audio is best heard when it is sped up. Please use your headphones, but be wary of the volume! Every pop or crack you hear is an earthquake. This is the first 4 hours and 10 minutes of the earthquake swarm, which contained the largest events of the entire swarm. Enjoy!
Please click a post title to view the data pertaining to that event!