Fig. 4: Mollweide projection of VGPs centred on 180° longitude.
From: Intermittent non-axial dipolar-field dominance of twin Laschamp excursions
a VGP-path for the Laschamp to the post-Laschamp excursions, as recorded in Lake Suigetsu, and excursional VGPs from lava flows related to the Laschamp Excursion. The lava-flow VGPs are from France6, 7, 19, Iceland9, 61, New Zealand10, 11, 62 and Japan63. The small black numbered dots show the sites of samples. b VGP clusters for the Laschamp Excursion centred in the North Pacific (NP), the South Pacific (SP), the Southern Indian Ocean (SI) and eastern Africa (EA). The dotted circle indicates a possible cluster (see text) around Australia. The symbols are the same as (a). c Comparison of VGP paths. Aqua colour; the Lake Suigetsu data filtered with an exponential lock-in rate function with a Z1/2 of 1.5 cm and condensed to a resolution of 45-yr per data point (Fig. 3b). Black colour; the Black Sea Laschamp data4, 48. The solid/open circles represent excursional/non-excursional VGPs. The red/brown open symbols represent the peak of the precursor (triangle), the start (circle) and the end (square) of the main excursion for the Lake Suigetsu/Black Sea data. d Time-averaged radial field component at the core-mantle boundary of the time-varying spherical harmonic model (CALS3k.4b) spanning 1000 BC to AD 1990 (adapted from ref. 50).
