Abstract
By means of the time derivatives of Global Navigation Satellite System (GNSS) carrier-phase measurements, the instantaneous velocity of a stand-alone, single GNSS receiver can be estimated with a high precision of a few mm/s; it is feasible to even obtain the level of tenths of mm/s. Therefore, only data from the satellite navigation message are needed, thus discarding any data from a reference network. Combining this method with an efficient movement-detection algorithm opens some interesting applications for geohazard monitoring; an example is the detection of strong earthquakes. This capability is demonstrated for a case study of the 6.5 Mw earthquake of October 30, 2016, near the city of Norcia in Italy; in that region, there are densely deployed GNSS stations. It is shown that GNSS sensors can detect seismic compressional (P) waves, which are the first to arrive at a measurement station. These findings are substantiated by a comparison with data of strong-motion (SM) seismometers. Furthermore, it is shown that the GNSS-only hypocenter localization comes close (less than a kilometer) to the solutions provided by official seismic services. Finally, we conclude that this method can provide important contributions to a real-time geohazard early-warning system.
Highlights
High-precision estimates of the instantaneous velocity of a Global Navigation Satellite System (GNSS) sensor (‘GNSS sensor’, ‘GNSS receiver’, and ‘GNSS station’ are used as synonyms) can be obtained based on time derivatives of GNSS phase measurements
The resulting velocity is in receiver-to-satellite line of sight (LOS), and primarily consists of LOS receiver and satellite velocity, receiver and satellite clock drifts, ionospheric and tropospheric rates, relativistic effects, as well as multipath and observation noise
It was demonstrated that estimates of the GNSS instantaneous receiver velocity can resolve seismic signals down to amplitudes of a few millimeters per second
Summary
High-precision estimates of the instantaneous velocity of a GNSS sensor (‘GNSS sensor’, ‘GNSS receiver’, and ‘GNSS station’ are used as synonyms) can be obtained based on time derivatives of GNSS phase measurements. This technique of GNSS velocity determination has been discussed for almost two decades in the geodetic literature, with a focus on applications in navigation [1,2,3,4,5,6]. The higher the sampling rate is set, the higher the noise level will be [7]
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