Do you have a link to where the USGS said it is of no concern? Because, strangely, they make no mention at all, that I can find, of this most recent activity on their Yellowstone-devoted page.
https://volcanoes.usgs.gov/volcanoes/yellowstone/
YELLOWSTONE VOLCANO OBSERVATORY MONTHLY UPDATE
U.S. Geological Survey
Friday, September 1, 2017, 2:13 PM MDT (Friday, September 1, 2017, 20:13 UTC)
YELLOWSTONE VOLCANO (VNUM #325010)
44°25’48” N 110°40’12” W, Summit Elevation 9203 ft (2805 m)
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREEN
Seismicity
During August 2017, the University of Utah Seismograph Stations, responsible for the operation and analysis of the Yellowstone Seismic Network, reports 1029 earthquakes were located in the Yellowstone National Park (YNP) region. The largest event was a minor earthquake of magnitude 3.3 on August 20, at 09:00 PM MDT, located about 10 miles north of West Yellowstone, MT, where the earthquake was reported felt. This earthquake is part of a continued energetic sequence in the same area that began on June 12.
August seismicity in Yellowstone was marked by the ongoing earthquake activity ~six miles north of West Yellowstone, MT, where an energetic swarm added an additional 894 locatable earthquakes to the 475 in July and 1028 earthquakes in June. The swarm includes the largest event of the month on August 20 (magnitude 3.3).
Swarm activity for August consists of five earthquakes in the magnitude 3 range and 69 earthquakes in the magnitude 2 range. Including the events from the prior two monthly reports beginning on June 12, total swarm seismicity includes one earthquake of magnitude 4.4, 12 in the magnitude 3 range, and 181 earthquakes in the magnitude 2 range. There are potentially thousands of additional earthquakes visible on the webicorders that cannot be located because they are too small or overlap another event, and they are not included in these numbers.
Additionally, August 2017 seismicity contained two separate small earthquake swarms
1) A small series of 34 earthquakes occurred August 14-18. The largest earthquake in the series (magnitude 2.7) occurred on August 14, 08:04 AM MDT, located nine miles north northeast of Old Faithful, WY.
2) A small series of 22 earthquakes occurred August 19 and 20. The largest earthquake in the series (magnitude 1.9) occurred August 19, 10:04 PM MDT, located 10 miles south of West Thumb, WY.
Earthquake sequences like these are common and account for roughly 50% of the total seismicity in the Yellowstone region.
Yellowstone earthquake activity is currently at elevated levels compared with typical background activity.
Ground deformation
Monitored locations within the Yellowstone Caldera show little change this month. Uplift north of the caldera, centered near the Norris Geyser Basin, continues at a low rate (a few millimeters per month), similar to what has been occurring since late 2015. Current deformation patterns at Yellowstone remain within historical norms.
An example of GPS data can be found at http://www.unavco.org/instrumentation/networks/status/pbo/data/WLWY (click on Static Plots / Cleaned)
The Yellowstone Volcano Observatory (YVO) provides long-term monitoring of volcanic and earthquake activity in the Yellowstone National Park region. Yellowstone is the site of the largest and most diverse collection of natural thermal features in the world and the first National Park. YVO is one of the five USGS Volcano Observatories that monitor volcanoes within the United States for science and public safety.
YVO Member agencies: USGS, Yellowstone National Park, University of Utah, University of Wyoming, UNAVCO, Inc., Wyoming State Geological Survey, Montana Bureau of Mines and Geology, Idaho Geological Survey
CONTACT INFORMATION:
Michael Poland, Scientist-in-Charge
mpoland@usgs.gov
https://volcanoes.usgs.gov/volcanoes/yellowstone/elevated.html
This article starts off with the statement about no concern.
This is a really good site for all types of events world wide. You can zoom in and get a lot of info when you choose a specific alert.
http://hisz.rsoe.hu/alertmap/index2.php
http://fox13now.com/2017/07/19/swarm-of-earthquakes-hit-yellowstone-national-park/
“The USGS puts the odds of a volcanic eruption at 1 in 730,000. Even if an eruption were to occur, it would likely result in lava flow rather than a cataclysmic explosion. Though this would have an effect on Yellowstone, it would not bring about the end of the United States as we know it.”
From this site: http://www.newsweek.com/montana-earthquake-yellowstone-supervolcano-632736