Regional Seismicity of the Northeastern Tibetan Plateau Revealed by Crustal Magnetic Anomalies

The northeastern Tibetan Plateau (NETP) is located at the front of the northeastward expansion of the Tibetan Plateau and is a tectonically active region with complex faults and intense seismicity. In this study, based on the high-order geomagnetic field model EMM2017, the crustal magnetic anomalies and Curie point depths (CPDs) in the NETP and adjacent areas were investigated. The relationship between the magnetic anomalies, CPDs, and seismic activity was assessed. The results show that strong earthquakes occur mainly in areas where the magnetic anomalies are negative or have a strong-to-weak transition. The CPD is located at 18–42 km. In the NETP, a shallow CPD corresponds to high heat flow. In contrast, in surrounding areas, a deep CPD corresponds to low heat flow. The northeast area from Bayan Har to the Qilian orogenic belt, and the region with a deep CPD in the Qaidam Basin, record the northeastward flow of the Tibetan Plateau. High-magnitude earthquakes are associated with depth changes in the CPD and areas with a shallow CPD. The frequent seismic activity in the NETP can be attributed to the northeastward flow of the Tibetan Plateau caused by a deep heat flux. The results can be used as a reference for the prediction of strong regional earthquakes.