Name
An improved crustal velocity model for Canada incorporating geophysical model constraints
Description
An improved national scale crustal velocity model is being developed for Canada that is part of an ongoing effort to update the realization of the Canadian Spatial Reference System (CSRS) to NAD83(CSRS) v8 and to support the implementation of the new North American Terrestrial Reference Frame of 2022 (NATRF2022). The new model is based on a reprocessing of all GPS data to the end of 2023 and includes data from continuous GPS stations throughout Canada, repeated high accuracy Canadian campaign data, as well as continuous GPS data from Alaska, the northern contiguous United States, and Greenland. Like the previous version, the updated velocity model is a ‘hybrid’ combination of geophysical model predictions constrained to GPS crustal velocity estimates, a feature that is particularly helpful in regions with sparser GPS data coverage and/or strong present-day deformation signals. The geophysical model inputs are predictions from glacial isostatic adjustment (GIA) and elastic deformation models that estimate the vertical velocity signal from present-day melting of ice sheets and glaciers. The GIA and present-day mass signals are combined with the GPS velocities to provide crustal velocity and uncertainty estimates for the north, east and vertical components. The resulting hybrid velocity model is an important part of the CSRS that enables users to propagate their coordinates to different reference epochs and can also be used to support studies of sea level change and natural hazards.