June 12 - Rapid Fire Swarm S of West Thumb Lake

Spectrogram plots detailing most of the June 12 rapid fire swarm (in order of time in UTC).

On June 12, 2019 a rapid-fire earthquake swarm struck in a linear pattern just south of West Thumb Lake. This is the largest rapid fire swarm to strike Yellowstone Caldera for the past few months. These types of events used to be somewhat rare, but have been increasing ever since 2017-2018. Many of these swarms are small, but some can reach many hundreds of events within a short time period. This post is the analysis page for this earthquake swarm. This post also contains seismic audio. Please click the title of this post or "read more" to continue...

USGS EQ Map

Yellowstone Seismic Stations

On June 12, 2019 at about 6:35UTC, a rapid-fire earthquake swarm struck just south of West Thumb Lake at Yellowstone Caldera in NW Wyoming. Swarms like these do occur from time to time, however we have not seen one this strong for a good few months. This swarm struck at a moderately shallow depth, between 2km and 7km, and struck the northern tip of the East Mount Sheridan Fault, mostly striking parallel to the fault system (as can be seen above).

Below I will show some seismic plots detailing most of this earthquake swarm. I will also post the seismic audio at the end of this post. If you wish to hear the seismic audio now, please scroll all the way down.

June 12, 2019 swarm:
 
Start of swarm: 06:35UTC
End of swarm: 07:10UTC (Total of 35 minutes, containing 2 separate bursts in seismicity.)
Info: The time of the earthquake swarm is stated above. Although it occurred over a 35 minutes time frame, there were several other micro-quakes after this time frame. Within the time frame stated above, there were two separate episodes of seismicity. The larger episode occurred first, lasting approximately 11 minutes. The smaller episode lasted approximately 8 minutes. Many smaller micro-quakes occurred between these two episodes as well.
Total earthquake count (includes even the tiniest, unreported events): ~80 events of all sizes. Most occurred as part of the first and second bursts in seismicity. Many were extremely small and there could be more than just 80 micro-quakes. It is hard to tell when they are so closely spaced in time.
Reported count: They are only reporting 12 earthquakes for the swarm area circled on the map in the beginning of this post.
Largest reported earthquake of this swarm: Largest event for the swarm area circled above was a M1.7 at 5.9km in depth.
Largest amplitude: ~18,900 (B944-EHZ), ~42,700 (YDD-HHZ)
Severity: Minor-Moderate

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. You can also find the locations of all stations at Yellowstone by looking for one of the two buttons 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. Severity is a personal determination, with the April 11, 2018 swarm acting as a sort of baseline for a major rapid-fire swarm. Severity ranges from minor, to moderate, to major. In rare cases, “extreme” will be used. However, I have not seen a rapid-fire swarm that could ever be labeled as such. But you never know what will happen in the future!

The following is the seismic audio to this earthquake swarm, taken from the seismic station used for the plots above. 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. Enjoy!