A scientific collaboration between researchers from the Trofimuk Institute of Petroleum Geology and Geophysics in Novosibirsk, Russia, the Volcanological Institute of the Canary Islands (Involcan) and the University of Granada (UGR) has revealed the secrets of the interior of the island of Tenerife through a new seismic tomography study, analysing the microseismicity located in the interior of the island, and identifying a “hot heart” of magma less than ten kilometres deep from the mouth of the Teide volcano.
This could be a precursor sign of an eruptive process on the volcano, in which the tomography shows that, in the crust below the Las Cañadas caldera, small magmatic reservoirs may be present at depths of less than five kilometres.
These reservoirs allow the magma to cool, changing its chemical composition towards phonolite, a potentially explosive type of magma, and can be a source of highly explosive eruptions, such as “the one that occurred at the Montaña Blanca volcano around 2000 years ago, which was of a sub-plinian type”.
At the same time, the study in which the UGR participates explains why the eruptions in Tenerife that occur outside the Las Cañadas caldera, along the northeast and northwest ridges, have a “more effusive character, and in these areas the magma cannot stagnate for a sufficient moderate weather to evolve towards a more explosive type”.
The results of this study have recently been published in the scientific journal Journal of Geophysical Research, published by the American Geophysical Society, and constitute an important tool for interpreting the increase in seismicity in Tenerife and the emission of carbon dioxide from the Teide crater, which Involcan has detected since the end of 2016.
This activity could be related to the slow ascent of a diapir, that is, a “bubble” of magma, to depths greater than ten kilometres below Teide. Therefore, this new knowledge will be of great use for a better interpretation of the precursor signals of a possible eruptive process in Tenerife.
This seismic tomography study was made possible by the launch in 2016 of the Canary Islands Seismic Network managed by Involcan, which currently has 19 broadband seismic stations that have made it possible to lower the capacity to detect and locate thousands of micro-earthquakes in Tenerife.
These data, together with those previously recorded by the National Geographic Institute, have made it possible to use seismic tomography to investigate the interior of the island to a depth of 20 kilometres and, more importantly, to determine the speed of seismic S waves, which are the most sensitive to the presence of hydrothermal fluids and magma.