Combining CHAMP and Swarm Satellite Data to Invert the Lithospheric Magnetic Field in the Tibetan Plateau

Abstract

CHAMP and Swarm satellite magnetic data are combined to establish the lithospheric magnetic field over the Tibetan Plateau at satellite altitude by using zonal revised spherical cap harmonic analysis (R-SCHA). These data are integrated with geological structures data to analyze the relationship between magnetic anomaly signals and large-scale geological tectonic over the Tibetan Plateau and to explore the active tectonic region based on the angle of the magnetic anomaly. Results show that the model fitting error is small for a layer 250-500 km high, and the RMSE of the horizontal and radial geomagnetic components is better than 0.3 nT. The proposed model can accurately describe medium-to long-scale lithospheric magnetic anomalies. Analysis indicates that a negative magnetic anomaly in the Tibetan Plateau significantly differs with a positive magnetic anomaly in the surrounding area, and the boundary of the positive and negative regions is generally consistent with the geological tectonic boundary in the plateau region. Significant differences exist between the basement structures of the hinterland of the plateau and the surrounding area. The magnetic anomaly in the Central and Western Tibetan Plateau shows an east-west trend, which is identical to the direction of the geological structures. The magnetic anomaly in the eastern part is arc-shaped and extends along the northeast direction. Its direction is significantly different from the trend of the geological structures. The strongest negative anomaly is located in the Himalaya block, with a central strength of up to −9 nT at a height of 300 km. The presence of a strong negative anomaly implies that the Curie isotherm in this area is relatively shallow and deep geological tectonic activity may exist.

Precursory worldwide signatures of earthquake occurrences on Swarm satellite data

“…The error of the magnetic field measured by Swarm satellites can be estimated to be less than 0.3 nT, with a typical value of 0.1 nT 50 .…”

A spherical cap model of the geomagnetic field over southeast Asia from CHAMP and Swarm satellite observations

“…The modeling of magnetic fields for an area using the SCHA or R-SCHA method using the magnetic field data obtained on satellites has also been of interest to many scientists, De Santis et al(1990), Qamili et al (2010). Recently, models of lithospheric magnetic field have been established using a combination of magnetic data obtained on some satellites (Swarm, CHAMP…) by Thébault et al (2013), Qiu et al (2017), Vervelidou et al (2018.…”

Initial scalar lithospheric magnetic anomaly map of China and surrounding regions derived from CSES satellite data

“…Their magnetic signature in southern Tibet attenuates quickly with altitude, and thus has no obvious relation to the broad satellite magnetic low. The formation of this wide magnetic low anomaly is considered to be caused by the high heat flow and shallow Curie depth below the southern Himalayan-Tibetan plateau [38,39].…”