Archeomagnetically determined values of inclination and declination are commonly reduced to a base location, the regional geomagnetic field being approximated either by the axial dipole or by a virtual dipole. We investigate the error in these approximations by using the spatial variations of the 1965 IGRF to simulate the temporal secular variation. The virtual dipole approximation is found to be significantly more accurate than the axial dipole approximation, particularly when the archeomagnetic site is at the same latitude as the base. Inclination error and declination error each have a normal distribution, but the directional dispersion is not circular-normal (Fisherian). Tables are pre-sented by which the statistical error in reduction of archeomagnetic directions to a base site can be readily estimated.The secular variation of geomagnetic inclination and declination over the past few milenia can be reconstructed by measuring the TRM of archeological baked clay. This has already been accomplished to varying degrees in several parts of the world, notably Is the "axial dipole" method of geographical correction used by Aitken and Weaver (1965), as good as the "virtual dipole" method used by Watanabe and DuBois (1965)? Our approach is statistical.We consider the geomagnetic field direction predicted for a site A from the field direction at a site B to be statistically distributed about the actual field direction at site A. The nature of the distribution will depend on the relative separation of the two sites and on the geographical correction method used to reduce the field at B to the site A. Time is not considered as a parameter, so we ignore the possibility of
It has become increasingly apparent that the large quantities of geophysical data being collected by modern instrumentation must be efficiently stored, processed, and displayed before meaningful interpretation can be undertaken. To meet these needs a man‐machine interactive computing system has been developed to provide the geophysicist with a direct communication link to the digital computer and methods for providing two‐ and three‐dimensional representations of geophysical data on cathode‐ray tubes (CRT). Gravity, magnetic, resistivity, and induced‐polarization responses have been modeled on the interactive system and displayed on a CRT. The interactive modeling processes allow the direct interchange of geophysical variables and data followed by the display of the recomputed models and corresponding theoretical responses. Model parameters can be monitored visually and continuously adjusted for a better solution. In addition, color‐shaded perspective views of three‐dimensional surfaces representing aeromagnetic, gravity, topographic, and correlative data also have been produced. Seismic data processing has been demonstrated for filter synthesis and convolution with interactive communication for program commands and data modification. Processed seismic sections have been displayed on a CRT in two‐dimensional, halftone views.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.