Data Event Response to the July 22, 2020 M 7.8 Simeonof, Alaska Earthquake
Written by Kathleen Hodgkinson, Dave Mencin, Beth Bartel, & Andi Ellis
Originally posted 22 July 2020
Last updated 28 July 2020
Event Summary
A magnitude 7.8 earthquake occurred at 06:12:44 UTC (22:12:42 local) on July 22, 2020, 105 km SSE of Perryville, Alaska. The earthquake is referred to by the Alaska Earthquake Center as the Simeonof earthquake. For more information, see the USGS Earthquake Hazards Program event page or the Alaska Earthquake Center event page.
The event occured within the Network of the Americas (NOTA) footprint. NOTA is a core component of the NSF Geodetic Facility for the Advancement of Geoscience (GAGE), operated by UNAVCO.
GAGE Response
NOTA GPS/GNSS Real Time Data Solutions
There are 41 real-time-enabled GPS/GNSS stations within 1550 km of the epicenter. Real-time stations continuously stream high rate (1-sps / 1 Hz) data to UNAVCO. Typical latencies for real-time stations, the time lapse between and observation being recorded on the receiver and it arriving in Boulder are less than 1 second. The radius is based on 2 cm predicted dyanamic displacements.
UNAVCO is downloading high-rate 1- and 5-sps (1 and 5 Hz) data from all NOTA GPS/GNSS stations within 1550 km of the epicenter. These data will be available in RINEX format from the UNAVCO high-rate data ftp site.
GAGE GPS/GNSS Displacement Estimates
The GAGE AC (MIT) inspects the NOTA GPS/GNSS daily positions for significant offsets when they have two to three days of post-event data. Offsets for this event are now available.
UNAVCO will produce a fully processed 1-sps borehole strainmeter (BSM) dataset for this event. This dataset can be downloaded from the UNAVCO borehole strainmeter event response page when it is ready. For an explaination of the strain plots (figures pending), see our Geophysical Event Response Data Explainer: Dynamic Strain.
Note: Figures and findings are preliminary and subject to revision.
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Figure 1. Map showing NOTA GPS/GNSS stations within 1550 km of the event epicenter. These data will be available for post processing from the UNAVCO high-rate data ftp site. Stations with real-time data streams are...Read more » -
Figure 2. Map showing only real-time NOTA GPS/GNSS stations within 1550 km of the event epicenter. (Figure by Kathleen Hodgkinson, UNAVCO)...Read more » -
Figure 3. Earthquake magnitude estimate calculated from the peak ground displacements (PGDs) measured by GPS/GNSS stations. The final magnitude calculation from the USGS based on seismic data is shown as a red dashed...Read more » -
Figure 4. Long-term tectonic velocities of GPS/GNSS stations in the Network of the Americas (NOTA) near the earthquake epicenter (orange star, approximate location from USGS). Pink scale bar in the lower left is 25...Read more » -
Figure 5. Real-time PPP solution for NOTA GNSS station AV09 generated by the GSeisRT software. (Figure supplied by Jianghui Geng, GNSS Research Center, Wuhan University)...Read more » -
Figure 6. On July 22, 2020 a thrust earthquake occurred offshore at 28 km depth within the Aleutian trench where the Pacific Plate subducts beneath the North American plate. The event caused coseismic movement of a...Read more » -
Figure 7. GPS time-series for station AC12 showing upward displacement of ~34 cm during the July 22, 2020 M 7.8 Simeonof, Alaska earthquake. (Figure supplied by William Hammond, Nevada Geodetic Laboratory, University of...Read more » -
Figure 8. GPS time-series for station AC28 showing downward displacement of ~7.5 cm during the July 22, 2020 M 7.8 Simeonof, Alaska earthquake. (Figure supplied by William Hammond, Nevada Geodetic Laboratory, University...Read more » -
Figure 9. Borehole seismic data from the NOTA borehole geophysics network. (Figure by Wade Johnson, UNAVCO)...Read more » -
Figure 10. Satellite interferometric phase changes (InSAR) following the M7.8 Simeonof, Alaska, earthquake are shown in the rainbow fringe patterns from a descending Sentinel 1 pass; GPS data are shown as vectors...Read more » -
Figure 11. Coseismic offsets of NOTA GNSS stations as calculated by the GAGE GNSS Analysis Center (MIT). Figure by Christine Puskas, UNAVCO)....Read more »
GAGE Data and Support
- Please contact archive-gps
unavco.org for information on data availability. - To request access to these and other RT-GPS stations operated by UNAVCO please send an email request to rtgpsunavco.org.
- For information on past event responses, see the UNAVCO Geophysical Event Response page.
Acknowledgements
These data are provided by the GAGE Facility, operated by UNAVCO, Inc., with support from the National Science Foundation and the National Aeronautics and Space Administration under NSF Cooperative Agreement EAR-1724794. The Network of the Americas (NOTA) is a core component of the NSF GAGE Facility. To acknowledge use of these data please follow the acknowledgment guidelines.
High-resolution Figures
- GPS/GNSS station download map (Figure 1)
- GPS/GNSS real-time station map (Figure 2)
- Magnitude estimate using GPS/GNSS peak ground displacement (Figure 3)
Related Links
- UNAVCO Geophysical Event Response page
- USGS event page
- Alaska Earthquake Center event page
- Network of the Americas
- UNAVCO GPS Velocity Viewer
- UNAVCO Geophysical Event Response Data Explainer: Dynamic Strain
Map Center:
Simeonof Island, Alaska
Last modified: 2020-08-24 10:37:56 America/Denver