Cyclic Behavior Associated with the Degassing Process at the Shallow Submarine Volcano Tagoro, Canary Islands, Spain

Abstract

Tagoro, the most recently discovered shallow submarine volcano on the Canary Islands archipelago, Spain, has been studied from the beginning of its eruptive phase in October 2011 until November 2018. In March 2012, it became an active hydrothermal system involving a release of heat and gases that produce significant physical–chemical anomalies in the surrounding waters close to the seabed. Fast Fourier transform (FFT) and wavelet time-domain-frequency analysis techniques applied to filtered time series of temperature, salinity, pressure, pH, and oxidation-reduction potential (ORP) data from a conductivity-temperature-depth (CTD) device mounted on a mooring and deployed at the deepest part of the main crater at a depth of 127 m, have been used to better understand the dynamic processes of the emissions during Tagoro’s degasification phase. Our results highlight that the hydrothermal system exhibited a stationary cyclic degassing behavior with a strong peak of a 140-min period centered on a significant interval of 130–170 min at 99.9% confidence. Moreover, important physical–chemical anomalies are still present in the interior of the main crater, such as: (i) thermal increase of +2.55 °C, (ii) salinity decrease of −1.02, (iii) density decrease of −1.43 (kg∙m−3), and (iv) pH decrease of −1.25 units. This confirms that, five years after its origin, the submarine volcano Tagoro is still actively in a degassing phase.