Data Event Response to the November 30, 2018 M 7.0 Earthquake, 13km N of Anchorage, Alaska

Written by David Phillips, Andria Ellis, and Shelley Olds
30 November 2018

Event Summary

A Mw 7.0 earthquake occurred at 17:29:28 UTC on November 30, 2018 (08:29:28 local), 13km N of Anchorage, Alaska. For more information, see the USGS Earthquake Hazards Program event and the Alaska Earthquake Center pages.

UNAVCO Response

GPS/GNSS Real-time Data Streams
Signals from this event were recorded by 22 GPS/GNSS stations within 1000 km of the epicenter operated by UNAVCO that were streaming high rate (1-sps / 1 Hz) data in real time (Figures 2 and 3). These data allowed peak ground displacements (PGD) to be calculated automatically from the displacement traces within seconds of the earthquake (Figure 3). Dynamic ground displacements of several centimeters were recorded by the real-time sites as the surface wave generated by the earthquake propagated away from the epicenter. The displacements were large enough and recorded by enough sites to determine the event to be ~M7 within 120s of the earthquake occurring. Note: figures and findings are preliminary and subject to revision.

GPS/GNSS Data - Custom Downloads for Post Processing
UNAVCO is downloading high-rate 1-sps (1 Hz) data from ~165 GPS/GNSS stations operated by UNAVCO within ~1500 km of the epicenter for a 3-day time window around the event (± 1.5 days). In addition, 5-sps (5 Hz) data will be downloaded from a subset of these stations for a 6-hour time window around the event (± 3 hours). A map of downloaded stations is shown in Figure 2. When downloaded, these data are available from the UNAVCO high rate data ftp site.

GPS/GNSS Displacements
Coseismic offsets from this event will be estimated by the GAGE GPS Analysis Center Coordinator (ACC), Professor Tom Herring (MIT). Preliminary offsets will be tabulated and published in an event (*.EVT) file available from the UNAVCO data products ftp site. As more data and final orbits become available, the ACC will also produce a “final” offset solution, as well as offsets estimated from Kalman filter time series analyses. Final and Kalman filter offset files will be added to the event file at the event products ftp site.

Borehole Strainmeter Data
UNAVCO has produced a fully processed 1-sps borehole strainmeter (BSM) dataset spanning the time period of this event. This dataset can be downloaded from the UNAVCO borehole strainmeter event response page.