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Data Event Response to the June 23, 2020 M 7.4 Earthquake 12 km SSW of Santa María Zapotitlán, Mexico

Written by Kathleen Hodgkinson, Dave Mencin, & Beth Bartel
Originally posted 24 June 2020
Last updated 21 July 2020

Event Summary

A magnitude 7.4 earthquake occurred at 15:29:05 UTC (10:29:05 local) on June 23, 2020, 12 km SSW of Santa María Zapotitlán, Mexico. For more information, see the USGS Earthquake Hazards Program 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. This portion of the network is run in partnership with Universidad Nacional Autónomo de México and others.

GAGE Response

NOTA GPS/GNSS Real Time Data Solutions
5 GPS/GNSS stations within 450 km of the epicenter were configured to operate in real-time during the event, i.e., continuously stream high rate (1-sps / 1 Hz) data to UNAVCO (Figure 1). 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.

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 600 km of the earthquake epicenter with available data for a 3-hour time window centered on the event (Figure 1). (Note that there are no NOTA stations 450-600 km of the epicenter.) When downloaded, 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 have been posted to the UNAVCO Data Products event page in file cwu_200623_1530_eq54_coseis_rapid.evt.

NOTA Borehole Strainmeter Data
UNAVCO will produce a fully processed 1-sps borehole strainmeter (BSM) dataset for this event (Figure 7). This dataset will be available from the UNAVCO borehole strainmeter event response page.

Note: Figures and findings are preliminary and subject to revision.

GAGE Outcomes

July 21, 2020: The GAGE facility would like to alert the community to the observation of an on-going rapid slip event that is occurring in the Oaxaca, Mexico section of the Cocos/North America subduction zone. The event is coincident with the 23 June 2020 M7.4 Santa María Xadani, Mexico earthquake. This region has shown non-volcanic tremor (NVT) and slow slips events in past. See GAGE AC note for more details.

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:
Santa María Zapotitlán, Mexico


Last modified: 2020-07-21  15:27:36  America/Denver