Abstract
Recent magnetic satellite missions facilitate new birth of large-scale geomagnetic field models and their applications to tectonics. Here, we directly compare the global geomagnetic field models NGDC-720 with the tectonics and seismicity in Mainland China and surroundings. It is found that the tectonics and seismicity in this area show remarkable correlation with the vertical component of lithospheric magnetic field (Bz) calculated at an altitude of 200 km. Previous thought was that earthquakes are more likely to occur in zero Bz belts or in obvious anomaly gradient belts. On the contrary, we find that more than half (53.2%) of the earthquakes occurred in areas with Bz of − 5 to − 3 nT or in areas with a relatively small horizontal gradient of Bz in the same time interval with the satellite data. The percentage seismic energy in these areas (− 5 nT < Bz < − 3 nT) is even as high as 94.6%. We explain this unexpected result with a two equivalent source dipole model, arguing that the viscosity difference caused by the temperature gradient within the lithosphere likely accounts for the correlation between magnetic anomalies and seismicity.
Highlights
From 1999 to 2009, three magnetic satellites, Ørsted, SAC-C, and CHAMP, were launched along with gravitational satellites, causing Christensen et al (2009) to call this period the geopotential decade
Because global and regional lithospheric magnetic field (LMF) models are valuable for plate tectonics and lithospheric dynamics, these new satellite observations and new
We propose a two equal source dipole (TESD) model to explain the correlation between seismicity and LMF
Summary
From 1999 to 2009, three magnetic satellites, Ørsted, SAC-C, and CHAMP, were launched along with gravitational satellites (including CHAMP), causing Christensen et al (2009) to call this period the geopotential decade. Active blocks, faults, GPS movements and lithospheric strength in Mainland China all have close correlations with Bz. Boundaries of obvious magnetic anomalies often signify boundaries of active blocks or large faults (Fig. 3). Earthquakes with all the three types of focal mechanisms could occur on the boundaries of positive or negative magnetic anomalies.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
