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Roland G. Henderson

Publications and source records attributed to Roland G. Henderson.

5 recordsLinked to original sources
USGS2014

Magnetic anomalies at high altitudes

To investigate the effect of anomalies in the Earth's magnetic field at high altitudes , aeromagnetic maps of two representative areas showing isanomalic curves for total intensity are projected to levels of 10 and 20 miles above the surface of a plane Earth. The projections are accomplished by numerical computations and by use of a magnetic ‐field projecting machine at the Naval Ordnance Laboratory. It is found that anomalies of 500 gammas near the surface of the Earth, in merging into neighboring anomalies , may produce effects of 100 gammas or more at an altitude of 20 miles.

Eos, Transactions, American Geophysical Union↗
USGS2006

Field continuation and the step model in aeromagnetic interpretation

Downward continuation of the field in the neighborhood of a singularity of a magnetic anomaly is used to render the anomaly more two‐dimensional, to make the bottom of the causal body more remote, and to obtain an auxiliary function, φ (O, z), by means of which the anomaly may be interpreted in terms of an equivalent vertical contact or step model. The concept of “apparent depth” is introduced and used in studying depth extent and susceptibility. The methods are illustrated with theoretical and practical examples.

Geophysical Prospecting↗
USGS1956

A preliminary report on model studies of magnetic anomalies of three-dimensional bodies

Model experiments were made to devise a rapid method for calculating magnetic anomalies of three-dimensional structures. The magnetic fields of the models were determined using the equipment at the Naval Ordnance Laboratory, White Oaks, Md. An irregularly shaped mass was approximated by an array of prismatic rectangular slabs of constant thickness and varying horizontal dimensions. Contoured maps are being prepared for these magnetic models at different depths and for several magnetic inclinations. The fields of these three-dimensional structures are obtained by superimposing the appropriate contoured maps and adding numerically the effects at each point. The equipment and laboratory methods are described. Theoretical and practical examples are given.

Geophysics↗
USGS1949

The computation of second vertical derivatives of geomagnetic fields

Second vertical derivatives of magnetic fields, because of their high resolving power, are often very useful in interpreting magnetic anomalies. Formulas are developed which permit their ready numerical computation. Comparisons are made between the resulting approximate values and the rigorous values obtained for simple idealized fields. The similarity between maps of second vertical derivatives of fields and those of certain types of residual fields is discussed.

Pennsylvania↗