Application of the Global Positioning System to the Assessment of Crustal Deformation in the Charlevoix Seismic Zone

Virgilio B. Mendes and Richard B. Langley

Abstract:	The Charlevoix Seismic Zone (CSZ) is historically the most seismically active zone in eastern Canada. It is defined by an area of approximately 35 km x 80 km, developing parallel to the St. Lawrence river, about 100 km northeast of Quebec City. The repetitive nature of large earthquakes in this region, which may presage the occurrence of a future major earthquake, lead to the implementation of extensive geodetic and geophysical monitoring beginning in 1974. The geodetic monitoring of crustal deformation in the CSZ has been carried out using several different techniques: precise gravity, level- ling and horizontal control. Since 1987 the Global Positioning System (GPS) has also been used in the zone. Given its high relative accuracy, a significant improvement in the knowledge of strain accu- mulation in this region is expected. The two GPS campaigns carried out in the CSZ by the Geodetic Survey of Canada have been analyzed using UNB’s DIPOPprogram package. The first campaign was carried out in 1987, using Texas Instruments Tl 4100 receivers. The second campaign was carried out in 1991, using Ashtec XII P-code receivers. Based on the assess- ment of the results of the different analysis approaches, we remark on the effect of the inclusion of surface meteoro- logical data, estimation of zenith tropospheric delay, and use of precise orbits on small networks. Taking advantage of DIPOP’s sequential adjustment approach, we analyzed the convergence of the baseline solutions with respect to the final coordinates and we draw some conclusions on the importance of a full constellation on precise positioning. Finally, wediscuss strategies tobe followed in futureGPS campaigns in the CSZ, in order to improve the accuracy of GPS-derived strain measurements.
Published in:	Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993) September 22 - 24, 1993 Salt Palace Convention Center Salt Lake City, UT
Pages:	1205 - 1219
Cite this article:	Mendes, Virgilio B., Langley, Richard B., "Application of the Global Positioning System to the Assessment of Crustal Deformation in the Charlevoix Seismic Zone," Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993), Salt Lake City, UT, September 1993, pp. 1205-1219.
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