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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.

NOTA GPS/GNSS High-Rate Data for Post Processing
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.

NOTA Borehole Strainmeter Data
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.

GAGE Data and Support

  • Please contact archive-gpsunavco.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.


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

Related Links

Map Center:
Simeonof Island, Alaska


Last modified: 2020-08-24  10:37:56  America/Denver