Using a volcanic monitoring data set from Ubinas volcano, we applied a process-based model of pre-eruptive seismic patterns to the 2019 eruptive episode with the goal of identifying possible seismic precursors in order to help forecast future eruptions. This conceptual model, based on geologic processes, is divided into four seismicity stages: Stage 1. Characterized by the occurrence of deep seismicity associated with deep intrusion(s); Stage 2. Occurrence of distal volcano – tectonic seismicity in response to magma intrusion(s) into the upper crustal reservoir; Stage 3. Dominated by seismicity associated with vent – clearing; and Stage 4. Corresponding to the occurrence of repetitive seismicity related with final magma ascent.
In the 2019 eruptive episode, we identified the last three stages: seismicity associated with the intrusion of new magma (Stage 2), seismicity associated with an opened and vent – clearing inside of the volcanic system (Stage 3) and repetitive seismicity that suggested the magma ascent towards shallower depths (Stage 4), however, no surficial lava was observed. Because Ubinas is an active system with frequent eruptions, Stage 2 was very brief; however, we were still able to identify the transition from phreatomagmatic to magmatic activity.
The model allows us to provide a process-based interpretation to the volcanic monitoring observations from Ubinas volcano. Additionally, this model will aid in future assessment of unrest and contribute to eruption forecasting.
