The real-time capture of seismic waves plays an important role in rapid source and rupture inversion, which is crucial for earthquake and tsunami early warning systems. Traditional methods of integrating Global Positioning System (GPS) and accelerometer data for real- time seismology are based on the GPS relative positioning and precise point positioning techniques and rely on either GPS reference stations or precise satellite orbit and clock products. We present a new method of integrating GPS and accelerometer data based on the GPS variometric approach. The variometric approach is based on time single- differences of GPS carrier phase observations and can estimate velocities and displacements using only the broadcast ephemeris and a single receiver. Collocated 1-Hz GPS and 200-Hz accelerometer data from the 2016 M W 7.8 Kaikōura earthquake were analyzed to verify the effectiveness of our method. Results reveal that this method can provide broadband and more accurate velocities and displacements qualified to detect P- wave arrivals. Moreover, this method can effectively avoid the aliasing problem present in the 1-Hz GPS waveforms. Taking the post-processed displacements from precise point positioning as a reference, this method can provide displacements with accuracies of 2.4, 2.5 and 3.7 cm in the east, north and up components, respectively.