Written by David Phillips and Beth Bartel
23 January 2018
A Mw 7.9 earthquake occurred at 09:31:42 UTC on January 23, 2018 (00:31:42 local), 280km SE of Kodiak, Alaska.
For more information, see the USGS Earthquake Hazards Program event page.
GPS Real-time Data Streams
Signals from this event were recorded by 16 UNAVCO GPS stations 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), with a magnitude derived from inverting the PGDs of M7.8. Note: figures and findings are preliminary and subject to revision.
GPS Real-time Stations Used
AC67 AC20 AC44 ATW2 AC53 AC11 AB43 AB44 AB50 AV34 AV39 AV26 AB53 AB49 AV24 AV09 AB18 NEAH P401
GPS Data - Custom Downloads for Post Processing
UNAVCO is downloading high-rate 1-sps (1 Hz) and 5-sps (5 Hz) GPS/GNSS data from Plate Boundary Observatory stations within 2,000 km of the epicenter for a 6-hour time window around the event (± 3 hours). A map of GPS stations being downloaded is shown in Figure 2. These data will be available from the UNAVCO high rate data ftp site.
Tom Herring (MIT), the GAGE GPS Analysis Center Coordinator (ACC), has estimated preliminary coseismic offsets associated with the 2018-01-23 M7.9 Kodiak, AK earthquake. Individual station offsets are tabulated in a “rapid" event (*.EVT) file available from the event products ftp site. The horizontal displacements in this event file are plotted in Figure 9. As more data 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, available from the PBO borehole strainmeter event response page.
USGS ShakeMap for the January 23, 2018 Mw 7.9 earthquake 280km SE of Kodiak, Alaska. (Figure from USGS.)...Read more »
Map showing continuous GPS/GNSS stations (circles/squares) near the epicenter (yellow star) of the January 23, 2018 Mw 7.9 earthquake 280km SE of Kodiak, Alaska. UNAVCO has downloaded available high-rate...Read more »
Preliminary real-time GPS/GNSS results and magnitude estimate calculated from the geodetic data for the Mw 7.9 earthquake 280km SE of Kodiak, Alaska. Traces show the 1-sps (1-Hz) displacements generated by...Read more »
Preliminary measured and predicted displacements from the 2018-01-23 09:31:42 UTC M 7.9 earthquake located 280km SE of Kodiak, Alaska. Magenta arrows are the predicted displacements derived from the...Read more »
Long-term velocities (blue arrows) of GPS/GNSS stations in the region around the epicenter (red star) of the January 23, 2018 Mw 7.9 earthquake 280km SE of Kodiak, Alaska calculated by the GAGE GPS Analysis...Read more »
Long-term velocities of GPS/GNSS stations in Alaska as calculated by the GAGE GPS Analysis Center Coordinator (continuous stations operated by UNAVCO, red arrows), and the University of Alaska Fairbanks...Read more »
1-sps shear strains recorded by PBO strainmeters from the 2018 January 23, 2018 Mw 7.9 earthquake 280km SE of Kodiak, Alaska.(Figure/Kathleen Hodgkinson, UNAVCO)...Read more »
Data from many GPS stations have arrived since the earthquake and these have been processed at the Nevada Geodetic Laboratory (NGL) using rapid orbits from JPL. NGL used these data to make 24 hour sample rate...Read more »
Preliminary GAGE Analysis Center Coordinator horizontal displacement solutions from GPS sites near the 2018-01-23 M7.9 Kodiak, AK earthquake. These “rapid” coseismic offsets were estimated from...Read more »
UNAVCO 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.
Gulf of Alaska