May 28 - West Thumb Lake

A minor rapid-fire swarm was detected on May 28, 2019 at West Thumb Lake and Yellowstone Lake. I will detail that swarm here. Please click the title of this post or "read more" to continue...

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Another minor rapid-fire swarm struck just to the northeast of West Thumb Lake, possibly in between West Thumb Lake and Yellowstone Lake. As of right now, 21:00UTC May 29, 2019, no earthquakes have been reported for this minor swarm. According to the P/S wave arrivals, I determined as best as I could that the swarm possibly took place somewhere within the black circle on the map above. Seismic audio of the main burst of this swarm is provided at the end of this post.

If you wish to see all the locations for all seismic stations at Yellowstone, please CLICK HERE. If you wish to see the USGS EQ map for this location and time period, please CLICK HERE. Although no quakes have been reported yet, they might report some in the future so check back to the USGS EQ map from time to time.

Details of this swarm are shown below, including many plots. But before I start, I want to show you a strange emergent seismic event that occurred as part of this swarm. As you can see below in the screenshot from WAVES (the green seismograms), it was a real seismic event that did appear on some of the neighboring stations:

Three plots from seismic station YLT detailing this strange emergent event.

Some odd hours prior to the start of the swarm, there were some random earthquakes that likely occurred near the epicenter of the swarm itself. These are detailed below:

May 28, 2019 swarm details (UPDATE AT END OF POST; SCROLL DOWN):
 
Start of swarm: 00:34UTC
End of swarm: 04:44UTC (Total of 4 hours and 10 minutes, though main burst lasted only 7 minutes.)
Info: Although the start and end of the swarm is stated above, the main burst of the swarm was very concentrated. The main burst started at 00:43UTC, lasted about 7 minutes, and contained no more than 30 micro-quakes. The details on this page, including the plots below, will be for the entire swarm (time period stated above).
Total earthquake count (includes even the tiniest, unreported events): ~70 (revised from 80) events for entire swarm, but many were extremely small, but 30 occurred in only 7 minutes.
Reported count: Only 2!
Largest reported earthquake of this swarm: M0.4 at 2.0km depth
Largest amplitude: ~2,200 (B944-EHZ), ~12,600 (YLT-EHZ)
Severity: Minor
 
Total earthquake counts are estimated by using P/S wave identification. Just because a very tiny earthquake occurred, doesn't mean that it can be located. Total earthquake counts are to show the total seismicity, not the locatable seismicity. Also, if you wish to see which earthquakes in the plots below were reported, simply go to the link I provided in the beginning of this post 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, so it makes it easy to correlate any events to the events shown in the plots below. You can also find the locations of all stations at Yellowstone by looking for the link I posted in the beginning of this post. Also, I do not detail every single event of the swarm in the plots below. However, I do try to show most of them.

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Here is seismic audio from seismic station YLT for the main burst of the earthquake swarm that struck West Thumb Lake on May 28, 2019. Please use your headphones but be wary of the volume! Plots of the main burst are shown below and the audio is right after that.

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UPDATE as of 3:00UTC June 1, 2019: They finally reported some events for this swarm. However, only 2 events were reported! We can clearly see there were many, many more than just 2 earthquakes. But I do understand many of the micro-quakes in this swarm were barely detectable on more than 3 surrounding stations. Regardless, we can see more than 2 occurred. The image below shows the actual epicenter of this swarm, based on the 2 earthquakes they reported (notice my expected swarm epicenter was WAY off):