Evidence for weak geomagnetic field intensity prior to the Cretaceous normal superchron

Centroid-moment tensor (CMT) solutions are presented for 961 earthquakes occurring during 2001. The solutions are obtained using corrections for aspherical Earth structure represented by the whole-mantle shear-velocity model SH8/U4L8 of Dziewonski and Woodward [A.M. Dziewonski, R.L. Woodward, Acoustic imaging at the planetary scale, in: H. Emert, H.-P. Harjes (Eds.), Acoustical Imaging, vol. 19, Plenum Press, New York, 1992, pp. 785–797]. The model of anelastic attenuation of Durek and Ekstr?m [Bull. Seism. Soc. Am. 86 (1996) 144] is used to predict the decay of the waveforms.