Aug. 31 Swarm - Continuation of Aug. 29th's Rapid-Fire Swarm

PB_B944_--_EHZ

As expected, another rapid-fire swarm broke out virtually in the same location as the August 29, 2019 earthquake swarm. This swarm, the most recent on August 31, was about half of the strength and size as the August 29, 2019 swarm. In this post I will show the usual seismic plots and seismic audio. Could more swarms be on the way? It is possible, but I think the seismicity is calming down for now. However, those have been some famous last words for people in the past (including myself)!

Please click the title of this post or "read more" to continue...

USGS EQ Map

Yellowstone Station Map

First off, please click the USGS EQ map button above to view the USGS EQ map for this location and time period. Keep an eye on it to see if any quakes will be reported. Also, feel free to visit the Yellowstone station map via the button above.

On August 29, 2019, Yellowstone experienced the largest rapid-fire swarm since December 31, 2018. Then, only about 1 1/2 days later, another rapid-fire swarm broke out. It appears this is a continuation of the Aug. 29 swarm seeing it is the same type of swarm, however notably weaker, and occurred in the same SSW to NNE trend.

As stated in my previous post, which can be found if you CLICK HERE, the recent swarming along this fault system is probably due to magmatic fluid migration along the fault structure. The fast-paced and hot fluids likely caused many micro-failures along the faults in this area. Rapid-fire swarms such as these are usually indicative of fluid migration. The types of fluids are unknown to me at this time.

Below is some information pertaining to this earthquake swarm:

August 31, 2019 swarm:

Start of swarm: 12:36UTC
End of swarm: 14:24UTC (Total of 1 hour and 48 minutes. Main burst lasted about 30 minutes and contained most of the seismicity.)

Info: A few micro-quakes occurred before and after the time period stated above. This swarm is a continuation of the August 29, 2019 earthquake swarm. CLICK HERE to visit my analysis page on that swarm. Today’s swarm also likely occurred along the northern most section of the East Mount Sheridan fault system. It is possible this is related to magmatic fluid migration along the fault structure, therefore causing hundreds of micro-failures causing these earthquakes.

Total earthquake count (includes even the tiniest, unreported events): ~104 events of all sizes (Although many were very small, and some were not, this count could be lower than the actual count. This is due to many of the events being so closely spaced that they appear to be one event.)

Reported count: 9 (keep checking the USGS EQ map button above to see what has been reported)
Largest reported earthquake of this swarm: M2.3 at 5.2km in depth
Largest amplitude: ~57,800 (PB_B944_--_EHZ), ~24,000 (WY_YLT_01_EHZ)
Closest active seismic station to swarm: B944 in the PB network
Severity: Moderate short term rapid-fire swarm
Depth of swarm area: Between 1.7km and 5.2km depth.

Below are helicorder plots from the 6 closest seismic stations to this earthquake swarm:

Below are seismic plots of this earthquake swarm. Plots were generated by myself using data obtained through IRIS and by using the seismic program SWARM. Please pay attention to all chart labels first before you read the data. Within the slideshow below there are a total of 20 images.

I do not show every earthquake within this swarm, however I do try to show most of them. 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.

Also, about 7 hours prior to this swarm, there was a very short outburst of seismicity of only 4 or 5 small events, likely in the same location. This can be seen below:

The following is the seismic audio to this earthquake swarm, taken from the seismic station used for the seismic plots above. All seismic audio is best heard when it is sped up so it has been compressed. Please use your headphones, since it likely will be too quiet for computer speakers, but be wary of the volume! Every pop or crack you hear is an earthquake. Many thanks to IRIS for their wonderful TimeSeries tool which allows for seismic audio to be created. Enjoy!