Strain Pattern and Kinematics on Canary Islands from GNSS Time Series Analysis

Abstract

Following the 2004 seismic unrest at Tenerife and the 2012 eruption at El Hierro, the number of GNSS observing sites in the Canaries has remarkably increased making possible to obtain a more detailed picture of the displacement pattern and velocity maps useful to characterize the mechanism of the current deformation in that region. We review and interpret nearly 10 years of continuous GNSS data from MAGNET database to infer kinematics of the Canary sector of the Atlantic Ocean. In order to improve the velocities retrieved from the daily GNSS solutions we have computed the Common Mode bias from the whole data set and subtracted it from the time series of each site. Then, a lower standard error on the ITRF absolute velocities is achieved by reducing the scattering of the solutions around the linear trend. We thus image the strain patterns over the region using triplets of GNSS stations in triangular frames ranging the archipelago. From results, baselines between Tenerife and Gran Canaria undergo the largest elongations, about 10 , while in all the other directions these amount to 10 . Our interpretation turns out some evidences of the existence of a major crustal fracture in the central part of the archipelago, between Tenerife and Gran Canaria. This is in accordance with the observed clustering of the seismic activity and the recent magnetic studies as well, both supporting the idea that the genesis of Canary Islands might be conditioned by a strikeslip tectonic framework, probably related to Atlas tectonic features in Africa.