Modelling ground deformation in Tenerife (Canary Islands) during 2003-2010

Tenerife is the biggest island of the Canaries and one of the most active from the volcanological point of view. The island is geologically complex, and its main volcano-tectonic features are three volcanic rifts and the composite volcanic complex of Teide-Las Cañadas. The latter is located in the central part of the island at the intersection of Tenerife principal rifts. Teide volcano, with its 3718 m of elevation constitutes the most prominent topographical feature of the island. Being a densely populated active volcanic island, Tenerife is characterised by a high volcanic risk. For this reason, the island requires an advanced and efficient volcano monitoring system. Among the geophysical parameters that could be useful to forecast an oncoming volcanic eruption, the ground deformation is relevant for detecting the approach of magma to the surface.

This study aim is to analyse the ground deformation in the surroundings of the Teide-Las Cañadas complex.  For this purpose, we studied the ground deformation of Tenerife by using a set of Synthetic Aperture Radar (SAR) images acquired between 2003 and 2010 by the ENVISAT ASAR sensor and processed through a DInSAR-SBAS technique. The DInSAR SBAS time series revealed a ground deformation in the central part of the island, coinciding with the Teide volcano. A similar deformation was already evidenced by Fernández et al. (2009) from 2004 to 2005.

We investigated the source of this ground deformation by applying the statistical tool of Independent Component Analysis (ICA) to the dataset. ICA allowed separating the spatial patterns of deformation into four components. We attributed three of them to an actual ground deformation, while the fourth seems to be only related to the noise component of data. The first component (ICA1) displays a spatial pattern localised in Teide volcano neighbourhoods and consists of a ground uplift of few centimetres. The deformation associated with this component starts in 2005 and persists along the rest of the time series. The second component (ICA2) of the ground deformation is localised in the South/South-West part of Las Cañadas rim while the third component (ICA3) is localised to the East of Teide volcano. We performed inverse modelling to analyse the source of the ground deformation related to ICA1 to retrieve the location, the geometry and the temporal evolution of this source. The inversion was based on analytical models of ground deformation as well as on Finite-Element-Modelling. The result showed that the ground deformation is associated with a shallow sill-like structure, located beneath Teide volcano, possibly reflecting a hydrothermal reservoir. The knowledge of this source geometry could be of significant interest to better understand ground deformation data of possible future volcanic crisis.