Mitigating the Effect of the Ridgecrest Earthquakes on the USGS’s Automated Analysis of Global Positioning System Data

Jessica R. Murray, & Jerry Svarc

Submitted August 14, 2019, SCEC Contribution #9600, 2019 SCEC Annual Meeting Poster #235

The two largest earthquakes of the Ridgecrest sequence caused significant coseismic and ongoing postseismic displacement at regional GPS stations. Coseismic offsets exceed 0.5 meter at near-fault stations, and exceed 5 millimeters at stations ~240 km away. Displacements due to the Ridgecrest earthquakes have the potential to affect velocity estimates both through reference frame adjustments that are applied network-wide and in time series analysis that is used to estimate velocities for individual stations. USGS conducts automated GPS data processing and secular velocity field estimation for stations throughout the western U.S. Here we quantify the effect on our network velocity estimates of displacements at stations that define the regional filters we use for removing common-mode errors. For GPS stations that are affected by the earthquakes we also present a preliminary comparison of velocities estimated using only the pre-earthquake portion of each station’s time series to those obtained using their full time series but with additional coseismic and postseismic terms included in the time series analysis. These assessments are essential to maintaining the reliability of GPS data products distributed by the USGS Earthquake Science Center and also are directly relevant to the ongoing development of the SCEC Community Geodetic Model.

Key Words
Ridgecrest, GPS, CGM

Citation
Murray, J. R., & Svarc, J. (2019, 08). Mitigating the Effect of the Ridgecrest Earthquakes on the USGS’s Automated Analysis of Global Positioning System Data. Poster Presentation at 2019 SCEC Annual Meeting.


Related Projects & Working Groups
Ridgecrest Earthquakes