Anticipating volcanic eruptions using rescaled range analysis of volcano-tectonic seismicity.

The possibility of forecasting volcanic eruptions remains a major challenge for the volcanological scientific community. To date, various techniques based on volcano-tectonic seismicity, endogenous gas emission and satellite imagery have been widely applied in an effort to understand and anticipate short-term volcanic behaviour leading to eruptions. The rescaled range analysis (R/S) applied to time series of volcano-tectonic earthquakes is a quantitative method for determining the short-term and long-term memory of seismic activity during volcanic unrest. By using the Hurst exponent, it is possible to identify the precise transition from anti-persistence to persistence in volcano-tectonic earthquake time-series (VT) associated with volcanic dike ascent. We calculated the Hurst exponent of volcano-tectonic earthquakes during the 2021 Tajogaite eruption (La Palma, Canary Islands), the temporal evolution of the GEOS diagram and its correlation with the sustained dynamics of the volcanic eruption. Our study suggests that the volcanic unrest system transitions from anti-persistence to persistence approximately two days before the eruption, indicating a non-return point and the imminent onset of the eruption. Furthermore, we identified five magma deep injections during the eruption. The final stage and potential cessation of the eruption can also be inferred from the asymptotic trend of the Hurst exponent.