Residual magnetic intensity, Crescent City, California

1983 ◽  
Author(s):  
Keyword(s):  
Magnetic Intensity ◽  
Crescent City

Replacement of Tsunami-Damaged Crescent City Marina

Ports 2013 ◽  
2013 ◽  
Author(s):  
Ted W. Trenkwalder ◽  
Ward Stover ◽  
Richard Young
Keyword(s):  
Crescent City

AEROMAGNETIC FIELD TEST OF TOTAL INTENSITY UPWARD CONTINUATION

Geophysics ◽  
1971 ◽  
Vol 36 (2) ◽  
pp. 418-425 ◽  
Author(s):  
Angelo L. Kontis
Keyword(s):  
Dirichlet Problem ◽  
Field Test ◽  
Theoretical Basis ◽  
Numerical Evaluation ◽  
Integral Formula ◽  
Intensity Data ◽  
Magnetic Intensity ◽  
Normal Field ◽  
Area Of Interest ◽  
Upward Continuation

The theoretical basis for applying the upward‐continuation integral, [Formula: see text]z⩽0, (1) to total magnetic intensity data T(α, β) measured on the plane z=0 has been recently reviewed by Henderson (1970). To perform upward continuation in the spatial domain, weights or coefficients obtained by numerical evaluation of equation (1) (Peters, 1949; Henderson, 1960; Fuller, 1967) may be convolved with the total intensity anomaly T(α, β) to produce T(x, y, z) at heights z<0 (for z positive downward). The accuracy of upward continuation is, therefore, dependent on the validity of the numerical coefficients and of the assumptions required to show that T(α, β) satisfies the conditions of the Dirichlet problem for a plane. These assumptions are that the quantity sensed by a total‐intensity magnetometer is in the direction of the earth’s normal field and that this direction is invariant over the area of interest.

scholarly journals 3. Results of the Makerstoun Observations, No. II. On the Relation of the Variations of the Vertical Component of the Earth's Magnetic Intensity to the Solar and Lunar Periods.

1851 ◽  
Vol 2 ◽  
pp. 97-98
Author(s):  
J. Allan Broun
Keyword(s):  
Vertical Component ◽  
Vertical Force ◽  
Magnetic Intensity

The following results are deduced from the observations of the balance or vertical force magnetometer described in the Introduction to the Makerstoun Observations. The observations were corrected for temperature by a method previously described.

Experiments on the influence of the aurora borealis on the magnetic needle. By the Rev. James Farquharson, F. R. S. Minister of Al­ford, Aberdeenshire. In letters addressed to Captain Edward Sa­bine, Sec. R. S

1833 ◽  
Vol 2 ◽  
pp. 391-392
Keyword(s):  
Royal Society ◽  
Magnetic Intensity ◽  
Aurora Borealis ◽  
Magnetic Declination ◽  
Stop Watch ◽  
The Mind ◽  
Magnetic Needle

In the first letter, dated from Alford, Dec. 15, 1829, the author gives a description of the instrument which was furnished to him by the Royal Society for measuring the variation of the magnetic needle, and also the magnetic intensity; and of his mode of using it. The needle was so delicately suspended as to render changes in the declination as small as 10'´ very sensible. In his experiments on the magnetic intensity, the intervals of time occupied in the needle’s performing 50 oscillations, commencing with an arc of 12°, were noted by a stop-watch, in which the stop, being applied on the ba­lance, is instantaneous in its operation. The watch is again released from the stop at the commencement of a new observation; thus com­pensating, on the principle of the repeating circle, for any inaccuracy in the reading off, or any inequality in the divisions of the dialplate. The observations made on an Aurora borealis which appeared on the night of the 14th of December, are particularly detailed. On that occasion, the disturbance of the magnetic declination was so great, and so frequently changing from east to west, and the reverse, as to leave no doubt in the mind of the author of the reality of this influence. The needle, however, was affected at those times only when the fringes of the aurora were in such a position as to include the needle in their planes. It appeared to him, also, that the side towards which the needle declined, was the quarter where the aurora gave out the most vivid light.

scholarly journals PEMODELAN BAWAH PERMUKAAN MANIFESTASI MINERAL DENGAN METODE GEOMAGNETIK DAERAH PACITAN JAWA TIMUR

KURVATEK ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 25-33
Author(s):  
Fatimah Fatimah
Keyword(s):  
Image Data ◽  
Geological Structure ◽  
Magnetic Data ◽  
Magnetic Intensity ◽  
Magmatic Arc ◽  
The North ◽  
Ore Minerals ◽  
Ore Mineralization ◽  
Extensional Structure ◽  
Anomaly Map

Tulakan Subdistrict, Pacitan Regency, East Java Province. This area is part of the Southern Mountain Zone of East Java, which is the Sunda-Banda magmatic arc of Oligo-Miocene age, where there are alterations and indications of valuable ore minerals. Field magnetic data is taken in an area of 1 x 1 km, with the looping method on the grid trajectory within 200 x 100 m. Then, magnetic data correction and data processing were carried out with Oasis Montaj. From the magnetic anomaly map, the value of high magnetic intensity in the southern part is fresh (intrusive) andesit-dasitic rock as host rock which causes alteration, in the middle has a low magnetic intensity value which is in the direction of the relatively NE-SW river direction, whereas in the north with high intensity is fresh andesite lava. From the image data, it can be seen that the straightness pattern of the geological structure which is dominated by the extensional structure with the direction of NE-SW and E-W is the main trap of epithermal veins carrying ore mineralization mainly Cu, Pb in the study area.

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