EMAG2-VERSION3 - A NEW GLOBAL COMPILATION OF LITHOSPHERIC MAGNETIC ANOMALIES

The Earth Magnetic Anomaly Grid (EMAG2 v3) with a 2 arc-minute (approximately 3 km) resolution is a compilation of marine and airborne trackline magnetics, precompiled grids, and satellite data. 74.4 million data points provided by over 100 source institutions, 30+ precompiled grids, observatory based corrections, and satellite based long wavelength model (MF7) are combined to create a global map of lithospheric magnetic anomalies. Using the data provided from NCEI’s (formerly NGDC) GEODAS database and software provided by Geosoft this update to the previous EMAG2 model is completely data-driven (i.e., not partially model-driven like the previous EMAG2 version), readily updated, and all anomalies can be traced back to the source data. A web based map viewer and extract system to retrieve customized subsets of the latest grid is currently being developed.

Key features visible in this anomaly grid include: (1) lower amplitude anomalies near the equator consistent with lower core field intensity in this region, (2) highest anomaly intensities over old, cold cratonic lithosphere, (3) significant second-order complexity to the oceanic magnetic “stripes” associated with the formation of positive and negative polarity magnetic remanence at mid-ocean ridges.