VADASE: State of the Art and New Developments of a Third Way to GNSS Seismology
In recent years, extensive work has been done to effectively exploit Global Navigation Satellite Systems (GNSS) for estimating important earthquake parameters such as the seismic moment and magnitude (i.e. GNSS Seismology). The rapid and accurate assessment of these parameters is of crucial importance to achieve reliable tsunami generation scenarios and eventually dispatch an early warning. In this framework, Geodesy and Geomatics division (AGG) of Sapienza University of Rome developed a new approach to obtain in real-time the 3D displacements of a single GNSS receiver. This solution, called VADASE (Variometric Approach for Displacement Analysis Standalone Engine), utilizes the broadcast orbits and the time differences of the high-rate (i.e. 1 Hz or more) carrier phases observations to ascertain the receiver movements over short intervals at a few centimeters accuracy level in real-time.
First we summarize the state-of-art of VADASE. Then, we illustrate the most recent developments of the algorithm, which include model refinements, single frequency (L1) capability and functionality with Galileo real data. Finally, we present the first results of an automatic procedure enabled by VADASE real-time capabilities. The epoch-by-epoch displacements (i.e. velocities) of approximately 100 stations of the IGS (International GNSS Service) high-rate (i.e. 1 Hz) network are retrieved every 15 min using VADASE, and the whole network can be characterized in terms of noise level (ranging from 1 to 5 mm/s for the horizontal and from 2 to 10 mm/s for the height); on this basis, corresponding thresholds (i.e. 3-sigma) could be set up in order to highlight significant displacements caused by an earthquake and eventually raise a tsunami alarm.
KeywordsGalileo GNSS Seismology Real-time Single frequency VADASE
The authors thank the three anonymous Reviewers and the Editor in Chief for their valuable suggestions that helped improving the present work. The authors recognize the fundamental role of the International GNSS Service for delivering high-rate GNSS data in real time. The authors are indebted with Dr. Nicola Cenni, Prof. Paolo Baldi and Prof. Enzo Mantovani for providing the data of MO05 station. VADASE is subject of an international pending patent, generously supported by the University of Rome “La Sapienza”. VADASE was awarded the DLR (German Aerospace Agency) Special Topic Prize and the Audience Award at the European Satellite Navigation Competition 2010 and was partially developed thanks to 1-year cooperation with DLR Institute for Communications and Navigation at Oberpfaffenhofen (Germany).
- Benedetti E, Branzanti M, Biagi L, Colosimo G, Mazzoni A, Crespi M (2014) GNSS seismology for the 2012 Mw = 6.1 Emilia Earthquake: exploiting the VADASE algorithm. Seismol Res Lett 85(3):649–656. doi:10.1785/0220130094Google Scholar
- Bock Y, Agnew DC, Fang P et al (1993) Detection of crustal deformation from the landers earthquake sequence using continuous geodetic measurements. Nature 361(6410):337–340Google Scholar
- Bock Y, Genrich JF (2006) Instantaneous geodetic positioning with 10–50 Hz GPS measurements: noise characteristics and implications for monitoring networks. J Geophys Res 111(3):B03403. doi:10.1029/2005JB003617Google Scholar
- Branzanti M, Colosimo G, Crespi M, Mazzoni A (2013) GPS near-real-time coseismic displacements for the great Tohoku-oki earthquake. IEEE Geosci Remote Sens Lett 10(2):6265361, 372–376. doi:10.1109/LGRS.2012.2207704Google Scholar
- Colosimo G, Crespi M, Mazzoni A (2011a) Real-time GPS seismology with a stand-alone receiver: a preliminary feasibility demonstration. J Geophys Res 116(11):B11302. doi:10.1029/2010JB007941Google Scholar
- Colosimo G, Crespi M, Mazzoni A, Dautermann T (2011b) Co-seismic displacement estimation: Improving tsunami early warning systems. GIM Int 25(5):19–23Google Scholar
- Colosimo G (2013) VADASE: a brand new approach to real-time GNSS seismology. Lambert Academic Publishing AG & Co KG, 180 pp, ISSN: 9783845438382 https://www.lap-publishing.com/site/home/10
- Langbein J, Bock Y (2004) High-rate real-time GPS network at parkfield: Utility for detecting fault slip and seismic displacements. Geophys Res Lett 31(15):L15S20 1–4. doi:10.1029/2003GL019408Google Scholar
- Larson K, Bilich A, Axelrad P (2007) Improving the precision of high-rate GPS. J Geophys Res 112(5):B05422. doi:10.1029/2006JB004367Google Scholar
- Ohta Y, Kobayashi T, Tsushima H, Miura S., Hino R, Takasu T, Fujimoto H, Iinuma T, Tachibana K, Demachi T, Sato T, Ohzono M, Umino N (2012) Quasi real-time fault model estimation for near-field tsunami forecasting based on RTK-GPS analysis: application to the 2011 Tohoku-oki earthquake (Mw 9.0). J Geophys Res 117(2):B02311. doi:10.1029/2011JB008750Google Scholar
- Pondrelli S, Salimbeni S, Perfetti P, Danecek P (2012) Quick regional centroid moment tensor solutions for the Emilia 2012 (northern Italy) seismic sequence. Ann Geophys 55(4):615–621. doi:10.4401/ag-6159Google Scholar