Long Valley Caldera, a super-volcano which resides in Eastern California, saw a extremely intriguing rapid-fire swarm on June 15-16, 2019. These types of swarms are my favorite and are more prevalent at Yellowstone Caldera in Wyoming than Long Valley Caldera in Cali. This earthquake swarm was spaced into two episodes: one occurring early in the morning local-time on June 15 and the other burst occurred late at night on June 15 as well. I usually label dates/times by UTC, not PST, which is ahead of PST by about 7 hours. This post will contain seismic plots pertaining to this cool earthquake swarm. Please click the title of this post or "read more" to continue...
June 15-16 Rapid-Fire Swarm at LVC
So, this earthquake swarm was pretty interesting! The two buttons above will show you the reported events for this swarm, including both bursts, and the locations of all seismic stations within LVC (Long Valley Caldera). The map image shown above details the caldera boundary and the location of the earthquake swarm. Although this is likely considered one swarm, I will detail this swarm by both bursts of seismicity. Both bursts occurred in the same location, same approximate depth, and carried the same characteristics. However, both bursts were separated by approximately 13 hours or so.
Below are helicorder plots from 4 of the closest seismic stations to this earthquake swarm. You can see both bursts in seismicity quite clearly.
Start of swarm: 12:45UTC
End of swarm: 14:14UTC (Total of 1 hour and 29 minutes, though many of the earthquakes occurred very close together.)
Info: Station used for the plots below for the first burst was MCB, seeing it is much better at recording these events.
Total earthquake count (includes even the tiniest, unreported events): ~93 events of all sizes.
Reported count: 21
Largest reported earthquake of this swarm: M2.8 at 6.0km depth
Largest amplitude: ~320,800 (MCB-HHZ), ~2,100 (MCS-EHZ)
Second burst (June 16, 2019):
Start of swarm: 03:09UTC
End of swarm: 04:02UTC (Total of 53 minutes.)
Info: I had to use MCS for this second burst of swarming, sadly. This is because MCB, the best station to use for this swarm, was seeing some serious background interference during some of this swarm. MCS is a very old station, so the waveforms are going to look a little weird. However, the frequency content on the spectrogram and spectra plots are accurate.
Total earthquake count (includes even the tiniest, unreported events): ~53 events of all sizes.
Reported count: 15
Largest reported earthquake of this swarm: M2.5 at 5.7km depth
Largest amplitude: ~296,000 (MCB-HHZ), ~2,100 (MCS-EHZ)
If you wish to see which earthquakes in the plots below and above were reported, simply go to one of the buttons I provided somewhere above that shows you the USGS earthquake map for Long Valley 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 Long Valley 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 rapid-fire swarm at Yellowstone acting as a sort of baseline for any 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!
Sadly, no seismic audio is available for swarms at Long Valley. This is because the NCEDC, contrary to the IRIS DMC, does not allow for audio downloads.
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.