On August 15, 2019 at 19:46UTC, a M3.5 earthquake struck the southern border of Yellowstone National Park. This was the start of a 20 hour period of increasing seismicity for the United States and Canada. It was the largest earthquake to strike Yellowstone in just over 2 years and was detected on seismic stations hundreds of miles away.

During this time frame, about 4 1/2 hours after the M3.5 at Yellowstone, a M4.2 struck Manhattan, Montana, including multiple foreshocks leading up to the M4.2. Almost 2 1/2 hours later, a strange M4.1 struck in an odd location in Southeast Saskatchewan, Canada. Then, about 10 1/2 hours later, a strong M4.2 struck South Hutchinson, Kansas. Finally, the seismicity calmed after a M5.4 struck off the coast of Oregon along the Blanco Fracture Zone, approximately 2 hours and 23 minutes after the M4.2 in Kansas. All of these events can be seen on the helicorder above, which is from station YHH at Yellowstone.

So, what caused this apparent increase in seismicity? North America was somewhat calm prior to this, except for the occasional M3 or so in California. Were all of these just a coincidence? It is up to you, seeing I do not have the answer for that. I will, however, show some data pertaining to these seismic events. Please click the title of this post or "read more" to continue...

On August 1, 2019 at 01:22UTC, a M5.3 (M5.4) struck Northern Australia at 10km in depth. In this post, I will show you why I think this earthquake was very strange. For the magnitude and depth, I am using the determination from Geoscience Australia (basically the USGS of Australia). USGS only labels it as being 0.1 larger. Please click the title of this post or "read more" to continue...