Deep lithospheric and asthenospheric magnetic sources

We used to think that the sources of magnetic anomalies were all shallow (<10 km) however, recent high-quality satellite magnetic surveys show that anomalies arise from the integration of multiple sources at various distance from the earth’s surface. Shallow sources produce short wavelength anomalies whereas deep sources cause long wavelength anomalies.

 

In the past 15 years, I have led a change in the old paradigm that the mantle was too deep and too hot to be magnetic.