Comment on nhess-2022-164

Abstract

This study was aimed to build a multi-station automatic classification system for volcanic seismic signatures. This system was based on a probabilistic model made using transfer learning, which has, as the main tool, a pre-trained convolutional network named AlexNet. We designed four experiments using different datasets with data that was real, artificial, and two different combinations of these (combined 1 and combined 2). The experiment presented the highest scores when a process of data augmentation was introduced into processing sequence. Thus, the lack of real data in some classes (imbalance) dramatically affected the quality of the results, because the learning step (training) was over-fitted to the more numerous classes. To test the model stability with variable inputs, we implemented a k-fold cross-validation procedure. Under this approach, the results were more than optimal, considering that only the percentage of recognition of the tectonic events (TC) class was partially affected. The most valuable benefit of using this technique was that the use of volcano seismic signals from multiple stations provided a more generalisable model which, in near future, can be extended to multi-volcano database systems. The impact of this work is significant in the evaluation of hazard and risk by monitoring the dynamic evolution of volcanic centres, which is crucial for understanding the stages in a volcano’s eruptive cycle.