High-rate GNSS and Seismogeodesy
Continuously-monitoring GNSS (cGNSS) networks have developed since the early 1990's as an adjunct to surveys (campaigns) to observe crustal deformation with higher temporal resolution. Other applications became apparent, for example, GNSS meteorology. Initially, cGNSS networks operated at a 15-30s sampling rate and data were downloaded once per day. These data were used to create daily GNSS displacement time series some of which now extend nearly 30 years. High-rate data, ≥ 1 samples per second (1 sps – also expressed as “1 Hz”, 10 sps = 10 Hz), were first applied to study crustal deformation, specifically for small-aperture kinematic surveys of
freely slipping (creeping) geological faults (Genrich and Bock 1992) and subsequently for dynamic applications such as movement of ice sheets for climate studies, georeferencing of airborne lidar surveys (Zwally et al. 2002), GPS-Acoustics (GPS-A) for seafloor positioning (Yokota et al. 2016) and engineering seismology (Saunders et al. 2016). In the early 2000's, cGNSS networks began to be upgraded to high-rate observations and streamed and processed in real-time. "GNSS seismology" provides coseismic displacements, both static (permanent) and dynamic, during earthquake shaking (Bock et al. 2000; Nikolaidis et al. 2001; Larson 2009; Genrich and Bock 2006; Langbein and Bock 2004). A comprehensive archive of high-rate GNSS displacements, in seismic format, of 29 earthquakes from 2003-2018 with moment magnitudes of Mw 6.0-9.0 is described by (Ruhl et al. 2018). We also maintain an archive of these seismic displacements in text format and add new significant earthquakes to this historical record as they occur. Furthermore, we archive broadband seismogeodetic displacement and velocity waveforms, a product of the optimal combination of collocated high-rate GNSS and seismic data (Bock et al. 2011). Seismogeodesy provides a broadband seismometer that does not clip in the near field of seismic event, a measure of permanent displacement for rapid magnitude estimation, and an instrument that does not experience magnitude saturation for large earthquakes (Goldberg and Bock, 2018).