Calculation of normalized source strength using second derivatives of the vertical integral of total-field magnetic anomaly

Abstract

Normalized source strength (NSS) is often used to interpret remanence data owing to its low sensitivity to the direction of magnetization. However, calculations of NSS are unstable at low latitudes. Therefore, we have developed a new parameter called modified NSS (MNSS), in which NSS is calculated using the second derivatives of the vertical integration of a total-field magnetic anomaly, rather than using magnetic field components. This approach helps to stabilize the NSS calculation. MNSS is slightly dependent on the magnetization direction, but the calculation of the latter does not require geomagnetic field direction information, meaning that MNSS calculations are convenient and very stable even at very low latitudes or over the equator. Here, we develop test models and a field-based case study to illustrate the features and advantages of MNSS.