![]() The PPP GPS time-series have not been used until today as a tool to describe the surface oscillatory motion. 2014), accuracy which is sufficient to determine the surface displacement (Fig. GPS, which is accurate up to a few millimetres for high-frequency oscillations in differential mode (Psimoulis & Stiros 2008, 2012), is accurate at the centimetre level in PPP mode (Moschas et al. Precise point positioning (PPP) allows to monitor the motion of standalone GPS sites (Blewitt 2008 Ge et al. 2012), the studies listed above did not make use of real-time or near real-time data processing strategies. 2012), water vapour delays (Perler et al. 2013a), changes in ionosphere status (Ducic et al. 2015), tsunami generation for early warning (Blewitt et al. We explore whether GPS can contribute to GMPEs but also if the seismic source can be better characterized using long-period surface oscillatory motions.Īs seismic waveforms, GPS time-series provide insights into surface transients observed during seismic wave propagation or during a seismic rupture (Larson et al. For this reason, peak ground displacements (PGDs) are generally not available and proxies like the displacement response spectrum (DRS 10 s) are used (Cauzzi & Faccioli 2008). ![]() ![]() Nevertheless, few GMPEs for peak motions representative of long-periods are available in the literature due to the limited amount of broadband data (Cauzzi & Faccioli 2008). Ground motion prediction equations (GMPEs) predict that the peak motions representative of longer periods, such as the spectral acceleration (SA) at 3 s depend proportionally more on the event's magnitudes than PGA or PGV (e.g. The relationship between magnitude and peak ground motions of an event is distorted by the interaction between seismic waves and the structures (sedimentary basins, fault systems, etc.) sampled during their travel from the source (e.g. Peak ground accelerations and velocities (PGA, PGV) are routinely computed using seismic data in near real-time (minutes or less) in the 0.5–25 Hz frequency range (typically) in order to assess the possible consequences of an earthquake shortly after its occurrence. In the current study we investigate whether GPS is reliable and accurate in the determination of oscillatory ground motions (acceleration, velocity and displacement) for frequencies lower than or equal to 0.33 Hz. ![]() Koketsu & Miyake ( 2008) showed that long-period ground motion is also of interest for the increasing number of large civil engineering structures such as bridges and tall buildings since far-distance resonance and short-distance directivity could occur. In the field of engineering, high-rate GPS is used to determine the deformation or the motion of structures (bridges, high buildings, etc.) in time (Çelebi & Sanli 2002 Psimoulis et al. Satellite geodesy, Transient deformation, Earthquake ground motions, Surface waves and free oscillations, Early warning 1 INTRODUCTIONįor solid Earth investigation, high-rate GPS is nowadays an essential tool in the study of transient deformation, seismic source at depth, or accurate determination of strain rate and surface velocity fields.
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