DBPapers
DOI: 10.5593/SGEM2014/B22/S9.026

DETERMINATION OF POST-SEISMIC DECAYS FROM SELECTED GNSS AND SLR CO-LOCATED SITES

M. Sapota, K. Szafranek, Janusz Bogusz, Mariusz Figurski, Stanislaw Schillak, Grzegorz Nykiel
Wednesday 1 October 2014 by Libadmin2014

References: 14th International Multidisciplinary Scientific GeoConference SGEM 2014, www.sgem.org, SGEM2014 Conference Proceedings, ISBN 978-619-7105-11-7 / ISSN 1314-2704, June 19-25, 2014, Book 2, Vol. 2, 199-206 pp

ABSTRACT
The impact of earthquakes on the stability of time series on the selected GNSS and SLR co-located sites was investigated. After strong earthquakes and tsunamis many stations being the core of the ITRF (International Terrestrial Reference Frame) were affected by position discontinuities, which caused their temporal uselessness as the reference. As a consequence, the decrease of the quality of the network geometry also occurs. The Earth crust stresses and post-seismic relaxation damages occurring near the Earth surface can be mentioned as the main reasons of coordinates change. After the earthquake shape of time series can be described by curve line with dumping amplitudes (so-called “postseismic decay”). GNSS and SLR data from selected co-located sites were processed to investigate the optimal method of post-seismic decays determination as well as the time necessary for each station to attain the stability again. It should be stressed that during that time, such stations should not be taken into account as a reference. The changes of North, East and Up components from co-located sites were described mathematically by fitting exponential and logarithmic functions in order to choose the optimal method for each case. Analysis of these functions can be interpreted twofold: it could reveal main direction of seismic wave propagation for geophysical studies and time which station needs to regain its stability in order of being included again as a referenced one can be determined.

Keywords: earthquake, post-seismic relaxation, GPS, SLR