Unveiling the pre-eruptive seismic series of the La Palma 2021 eruption: Insights through a fully automated analysis

We have analyzed the seismic series that preceded the La Palma 2021 eruption using a fully automated workflow based on Deep Learning. A new seismic catalog has been obtained that contains twice the number of events as the original manual catalog. The new catalog consists of 5059 absolute locations obtained using a non-linear location method and a 3D velocity model of the island, as well as relative locations by means of double differences method. Our enhanced catalog contains detailed features of seismic migration through the crust. We differentiate the sequence into three stages leading up to the eruption onset using independent seismic parameters: inter-event time variation coefficient, b-value spatial distribution, hypocentral migration and magnitude distribution. Our analysis identifies two magmatic intrusions: The first migrates from the center of the Cumbre Vieja area to the west coast of the island (stage 1), where it stagnates. After two days of seismic quiescence (stage 2), a second intrusion begins near the center of the island and rises to the surface leading to the eruption (stage 3). These results were further validated by GNSS observations and previous geodetic studies. Our findings highlight the usefulness of this type of automated methodology, offering a real-time and accurate response during intense seismic episodes.