An adaptive Butterworth spectral-based graph neural network for detecting ionospheric total electron content precursor prior to the Wenchuan earthquake on 12 May 2008

In this study, Global Ionosphere Maps (GIMs) were used to detect all total electron content (TEC) precursors prior to the M-w 7.9 Wenchuan earthquake at 06:28:01 (UTC) on 12 May 2008. The GIMs were converted into GIM-gis between 00.00 (UTC) on 01 December 2004 and 31 March 2005 and were used to build the Spectral-Based Graph Neural Network (SB-GNN) and Adaptive Butterworth Spectral-Based Graph Neural Network (ABSB-GNN) models. A blurred TEC precursor was detected at 2:20 (UTC) on 9 May 2008, i.e. 3 days prior to the Wenchuan earthquake, using the ABSB-GNN model in place of the SB-GNN model, which improved predictive ability. After evaluating the variance in the learning process, the two models were verified for stability with better training and predicted accuracies in the ABSB-GNN model, which might be the reason that a blurred TEC precursor was detectable using the ABSB-GNN model.