Present day crustal deformation along the Magallanes-Fagnano fault system in Tierra del Fuego region by GPS

L. MENDOZA; R. PERDOMO; J. L. HORMAECHEA; D. DEL COGLIANO; R. DIETRICH; M. FRITSCHE; A. RICHTER

Buenos Aires

Congreso; Reunión Científica de la International Association of Geodesy, Geodesy for Planet Earth; 2009

Asociación Argentina de Geofísicos y Geodestas, Comité Nacional de la Unión Geodésica y Geofísica Internacional

GPS observations represent a useful dataset to monitor present day movements of the Earth’s crust. In this contribution we present results based on a GPS campaign data spanning 14 years, involving 30regional sites. The region under study is located in the southernmost part of South America, in Tierra del Fuego region (TDF), and include the Magallanes-Fagnano Fault System (MFFS), the only on-landsegment of the South American/Scotia tectonic plates boundary (SA/SC). For the analysis of data covering such a long time span the homogeneity of the required products (e.g. reference frame, satellite orbits, EOP, etc.) is imperative, otherwise significant systematic effects could propagate to the estimated parameters. For our computations, the Bernese GPS software with state-of-the-art strategies and models was used, and the products of the reprocessing of the IGS network PDR05(Steigenberger et al. 2006, Rülke et al. 2008) served as a homogeneous base for the derivation of site velocities.The site velocity vectors were determined for each station with an accuracy of less than 0.2 millimeters per year. The resulting densification of the global reference frame (position and velocity for each regional GPS site) was then used as pseudo observation to estimate the regional horizontal strain rate field associated to MFFS. We found an active deformation zone along a 30 km-wide belt centered on the main trace of the fault system, limited at north and south by geodynamically stable regions. The identification of these stable zones in either sides of the MFFS allows a more precise determinationof the relative transform velocity between the SA/SC tectonic plates in TDF. A a relative average velocity of 4.6 +/- 0.2 and -0.3 +/- 0.4 mm per year, in East and North direction respectively, was estimated. Finally, the results of the detailed strain analysis performed for the deformation zone will be discussed in the presentation.