Upper Bound to the Density Jump at the Boundary of the Earth's Inner Core

@article{Bolt1970UpperBT,
  title={Upper Bound to the Density Jump at the Boundary of the Earth's Inner Core},
  author={B. Bolt and A. Qamar},
  journal={Nature},
  year={1970},
  volume={228},
  pages={148-150}
}
THE Earth has an inner core about the size of the Moon. Convincing observations of the seismic waves PKiKP, reflected at steep angles from the inner core boundary (ICB), were announced by Engdahl et al. (annual meeting of the Seismological Society of America), using the Large Aperture Seismic Array (LASA) in Montana (epicentral distances Δ<40°). These identifications agree with expected travel times and wave slownesses1 (p = dt/dΔ), and pPKiKP minus PKiKP time lags.