Journal Article

Global Search of PKP Precursors With Graph Neural Network: Implications for Scatterers in the Lowermost Mantle

Sun, Daoyuan, Li, Jiewen, Li, Zefeng, Si, Xu, Ma, Shang, Su, Yulong, Zhu, Jun

2025

Overview

Seismic waves preceding the core phase PKIKP, known as PKP precursors, have been used to map small scatterers near the core‐mantle boundary (CMB). However, their low signal‐to‐noise ratio has required manual identification, hindering systematic and comprehensive analysis. Here, we develop GraphCursor, a model based on Graph Neural Networks (GNNs), to detect PKP precursors across multiple stations. Trained on manually picked precursors, GraphCursor identifies 37,512 precursor waveforms from 5,499 global earthquakes (2000–2024). We locate scatterers by stacking multistation probability functions and estimate their strengths relative to global averages. Our exhaustive search produces unprecedentedly abundant scatterers, including new discoveries of those beneath Antarctica. The distribution of most global scatterers largely correlates with ultra‐low velocity zones (ULVZs). GraphCursor's potential extends to identifying other deep seismic phases and aids in promoting the discovery of new deep Earth structures.

• Publisher: John Wiley & Sons, Inc
• Subject: Automation / Datasets / Deep learning / Earth mantle / Earth structures / Earthquake prediction / Earthquakes / Graph neural networks / Net losses / Neural networks / Neural stem cells / P-waves / Precursors / Probability / Seismic waves / Waveforms