Update about the ongoing Yellowstone earthquake swarm located on the southeast end of last summers (2017) Maple Creek Swarm. As of the night of February 18, over 200 earthquakes have been located in an area ~13 km (8 mi) NE of West Yellowstone, Montana. More information here.
On September 02, 2017, in eastern Idaho near the town of Soda Springs a magnitude 5.3 earthquake occurred that was widely felt throughout southeastern Idaho and northern Utah. This earthquake has been followed by a very active aftershock sequence. These earthquakes are slightly outside of the University of Utah Seismograph Stations area of responsibility, but the area is of interest to UUSS and the USGS Earthquake Hazards Program.
UUSS in partnership with USGS have deployed two UUSS 3-channel strong-motion systems and six USGS 6-channel seismic systems (broadband and strong-motion) within 50 km of the seismicity.
August 03, 2017 UPDATE: The University of Utah Seismograph Stations (UUSS) is monitoring an earthquake swarm which is currently active on the western edge of Yellowstone National Park. The swarm began on June 12th, 2017 and, as of 13:00 MDT on August 2nd, 2017, is composed of 1,562 events with the largest magnitude of ML 4.4 (MW 4.4) (Figure 1). The swarm consists of one earthquake in the magnitude 4 range, 8 earthquakes in the magnitude 3 range, 134 earthquakes in the magnitude 2 range, 505 earthquakes in the magnitude 1 range, 879 earthquakes in the magnitude 0 range, and 35 earthquakes with magnitudes of less than zero. These events have depths from ~0.0 km to ~14.0 km, relative to sea level. At the time of this report, there were 125 felt reports for the M4.4 event that occurred on June 16, 2017 at 00:48:46.94 UTC (June 15, 2017 at 18:48:46.94 MDT). The M4.4 event has an oblique strike-slip moment tensor solution (Figures 1 & 2). In addition, four other earthquakes in the swarm have been reported felt.
Figure 1. Location of the earthquakes that are part of the swarm as of August 3, 2017 at 01:00 PM MDT (red symbols).
Figure 2. Moment Tensor solution for the M4.4 event showing the fit between data (black) and synthetics (red dashed).
Figure 3. Animation of the June 2017 Yellowstone earthquake swarm. Earthquakes appear as red circles as they happen, then transition to blue. After they have occurred, they appear as black circles. The size of the circles are proportional to the earthquakes magnitude.
Earthquake swarms are common in Yellowstone and, on average, comprise about 50% of the total seismicity in the Yellowstone region.
UUSS will continue to monitor this swarm and will provide updates as necessary.
If you think you felt an earthquake, please fill out a felt report at: http://earthquake.usgs.gov/earthquakes/dyfi/.
Released: July 18, 2017 03:15 PM MDT
The University of Utah Seismograph Stations reports that a minor
earthquake of magnitude 3.6 occurred at 02:31 PM on July 18, 2017
(MDT). The epicenter of the shock was located 9.3 mi N of W.
Yellowstone, MT. This earthquake is part of an ongoing sequence
of earthquakes that began on June 12, 2017 and included a
a magnitude 4.4 event on June 15, 2017, 9.0 mi NNE of W.
Yellowstone, MT. Today’s M 3.6 earthquake was reported felt in
Yellowstone National Park and in West Yellowstone, MT. It was
followed by numerous smaller earthquakes, the largest of which
had magnitudes of 2.8 and 2.9. The total number of located
earthquakes in the current sequence has now exceeded 1200.
Anyone who felt the earthquake is encouraged to fill out a survey form
either on the Seismograph Stations website: www.quake.utah.edu or the
US Geological Survey website: earthquake.usgs.gov.
Earthquake Summary:
Date (UTC): July 18, 2017 Time (UTC): 20:31
Date (local): July 18, 2017 Time (local): 02:31 PM MDT
Latitude: 44 47.25′ N
Longitude: 111 2.27′ W
Preferred magnitude: 3.60 Ml
Shelly, D. R., D. P. Hill, F. Massin, J. Farrell, R. B. Smith, T. Taira, 2014, A fluid-driven earthquake swarm on the margin of the Yellowstone caldera, J. Geophys. Res., doi:10.1029/2013JB010481.