Evaluation of High-Rate GNSS-PPP for Monitoring Structural Health and Seismogeodesy Applications

This study evaluates the usability of the GNSS-PPP method for structural health monitoring and seismogeodesy applications. Two test scenarios were considered. The first test scenario included monitoring hormonic oscillations in amplitude of 5 mm to 20 mm with the frequency range of 0.2 Hz to 2.5 Hz that were generated using a shaking table, which has the ability to move in one direction in a horizontal plane. The second test scenario was carried out by simulating the El-Centro Earthquake as a seismogeodesy application. The used GNSS data comprised dual-frequency observations with a 10 Hz sampling rate. GNSS-derived positioning time series were obtained by processing the data using a post-mission kinematic PPP method and results were compared, in both the frequency domain and time domain, with LVDT (Linear Variable Differential Transformer) data, taking as a reference. Results show that the high-rate GNSS PPP method can capture the frequencies of harmonic movements comparable to the LVDT. The observed amplitudes of the harmonic oscillations are slightly different from the LVDT data at the order of mm level. These results demonstrate the ability of the high-rate GNSS PPP method to reliably monitor structural and earthquake-induced vibration frequencies and amplitudes for both the structural health and seismogeodesy applications

Long-period surface motion of the multi-patch Mw9.0 Tohoku-Oki earthquake

We show that it is possible to capture the oscillatory ground motion induced by the Tohoku-Oki event for periods ranging from 3 to 100s using Precise Point Positioning (PPP). We find that the ground motions of the sedimentary basins of Japan were large (respectively > 0.15m/s and >0.15m/s2 for velocity and acceleration) even for periods larger than 3s. We compare geodetic observables with a Ground Motion Prediction Equation (GMPE) designed for Japan seismicity and find that the Spectral Acceleration (SA) is well estimated for periods larger than 3s and distances ranging from 100 to 500km. At last, through the analysis of the displacement attenuation plots, we show that the 2011 Tohoku-Oki event is likely composed of multiple rupture patches as suggested before by time-reversal inversions of seismic data

Beyond 100: The Next Century in Geodesy

This open access book contains 30 peer-reviewed papers based on presentations at the 27th General Assembly of the International Union of Geodesy and Geophysics (IUGG). The meeting was held from July 8 to 18, 2019 in Montreal, Canada, with the theme being the celebration of the centennial of the establishment of the IUGG. The centennial was also a good opportunity to look forward to the next century, as reflected in the title of this volume. The papers in this volume represent a cross-section of present activity in geodesy, and highlight the future directions in the field as we begin the second century of the IUGG. During the meeting, the International Association of Geodesy (IAG) organized one Union Symposium, 6 IAG Symposia, 7 Joint Symposia with other associations, and 20 business meetings. In addition, IAG co-sponsored 8 Union Symposia and 15 Joint Symposia. In total, 3952 participants registered, 437 of them with IAG priority. In total, there were 234 symposia and 18 Workshops with 4580 presentations, of which 469 were in IAG-associated symposia. ; This volume will publish papers based on International Association of Geodesy (IAG) -related presentations made at the International Association of Geodesy at the 27th IUGG General Assembly, Montreal, July 2019. It will include papers associated with all of the IAG and joint symposia from the meeting, which span all aspects of modern geodesy, and linkages to earth and environmental sciences. It continues the long-running IAG Symposia Series