Hey guys! Welcome to my first blog post on my new website! Feel free to comment below, of course after clicking "read more". In this first post, I will simply talk about the minor earthquake swarm event which occurred on August 21, 2018 near Little West Thumb, Yellowstone Lake, Yellowstone, WY. As always, click "read more" on any of my blog posts to read more!
Post last updated: August 30, 2018
On August 21, 2018 from 7:53utc to 8:33utc (12:53am to 1:33am Pacific Time), a small but interesting earthquake swarm appeared at Yellowstone. Seismic data was retrieved from the 3 seismic stations which were closest to this event: H17A BHZ, YLT EHZ, and YML EHZ. Merging all three data files into the seismic program WAVES, and cross correlating only P wave arrivals, I came to the conclusion that about 20 identifiable earthquakes occurred from 7:53utc to 8:33utc with one lone earthquake occurring at 12:52utc. Most earthquakes were extremely small, most likely registering between -0.1 to 0.4 and occurring beneath the northern tip of West Thumb, Yellowstone Lake. However there were some earthquakes that were larger.
Sadly, only 3 earthquakes were reported for this event (seen in the image directly below)! There were definitely 15-20 earthquakes within this event. Don't believe me? Simply use WAVES, merge all three data files (email me if you want them), zoom in until the waveforms are spread out enough to identify P waves, and count all the P waves that appear on all three stations. Definitely at least 20 earthquakes. I am not saying all of them were locatable, just that they were identified as actual earthquakes due to their travel time to the 3 nearest stations. YLT seems to be the seismic station that was closest to this event.
Again, sadly they only reported 3 earthquakes for this event. Now they said the largest event was a magnitude 1.8. The amplitude of the largest event did seem to indicate a magnitude of 1.8 to 2.0. The three images below are the seismograms from this day showing the earthquake swarm. This post continues below the three images. Remember the swarm lasted from 7:53utc to 8:33utc with one lone earthquake occurring at 12:52utc. As always, UTC is the time period used on the right:
Although there were no low frequency earthquakes spotted, sometimes a sign of magmatic resonance or volcanic gas release within a small space, something you would most likely see during a magma injection event, I personally believe this was caused by hydrothermal fluids being aggravated by something. What else is down there besides dirt, rock, and hydrothermal fluids? Magma! I do not believe this was an intrusion event, but due to the rapid succession of earthquakes it seems tectonic activity alone was not the cause.
Including the earthquake swarm on July 5, 2018, there have been three separate rapid succession earthquake swarms right at West Thumb, Yellowstone Lake. The July 5 event seemed to contain the fastest occurrence out of all three events. I still believe the July 5 event was caused by magma injection. I will soon be doing an article about that within the "Seismic Events" page. The three rapid succession earthquake swarms at Yellowstone occurred at Little West Thumb on July 5, 2018, August 21, 2018, and August 26, 2018. So what is going on with West Thumb? Why do the earthquakes occur in a farther rapid pace than anywhere else within Yellowstone National Park? I do not have an answer to that... Yet! The images below are from the event on August 21, 2018. Please always remember to keep time frame into account! Need additional data or images regarding this event? Please email me!
Ben Ferraiuolo is a fast learner and someone who will always stand for the truth. Visit "About Me" for more!