Magnetic Anomalies Due to Prism‐shaped Bodies With Arbitrary Polarization

Bhattacharyya, B. K.

doi:10.1190/1.1439386

Cited by 277 publications

(160 citation statements)

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“…Now for any arbitrary polarization of intensity Ip, the total field d H at a point (x, y, 0) and its first and second vertical derivatives due to the prismshaped body are given by the following expressions (Bhattacharyya, 1964):…”

Section: Methods Of Analysismentioning

confidence: 99%

The Delineation of Deep Crustal Magnetic Bodies from Total Field Aeromagnetic Anomalies

Bhattacharyya

Morley

1965

J. geomagn. geoelec

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Studies were made of accurate, total field aeromagnetic data of excellent uniformity over an area in NW. Ontario extending from 4845'N to 53N latitude and from 86W to 94W longitude. The rocks in this area are of early Precambrian age (Archaean era). The regional effects from the data were removed. The residual values were then analytically filtered to obtain the total field stripped of its near-surface, high amplitude components. Eighty-five individual anomalies were selected and analyzed to determine the horizontal dimensions and the depths to the tops and bottoms of the causative bodies and the magnitude and direction of total polarization vectors associated with the bodies. The bodies were assumed to be vertical rectangular prisms of arbitrary polarization. A brief summary of the method used is presented.The horizontal dimensions of the bodies vary from 0.8 km (.5 milez to 5.1 kms (3.2 miles). The depths to the top of the bodies in the filtered aeromagnetic map are found to be in the range 4.8 kms (3 miles) to 8 kms (5 miles) from the surface of the ground. The depths to the bottom of the bodies are between 17.7 kms (11 miles) and 24 kms (15 miles) for most of the anomalies, with a mean depth of 20 kms (12.4 miles), which is interpreted as the mean depth to the Curie point geotherm. The horizontal vectors of the polarizations are subparallel to the magnetic lineation of the filtered aeromagnetic map. An interesting and surprising result of this analysis is the detection of the presence of alternatingly normal and reverse polarization roughly in the East-West direction. The mean inclination and declination for normal polarizations are 67.6 and 258.7 respectively whereas those for reverse polarizations are -67.9 and 81.3 respectively. The consistency in the directions of magnetization in the two clusters for normal and reverse polarization indicates strongly the absence of any dominant component of magnetization parallel to the present field. On the basis that the magnetizations are permanent and the reversals are due to field or selfreversal, the calculated pole position for the rocks of Archaean era is found to be at a latitude of 31.5 N and a longitude of 136.9 W. The intensity of magnetization of the bodies lies within a wide range from. 0006 to. 349 cgs emu with the average of. 055 cgs emu.

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Section: Methods Of Analysismentioning

confidence: 99%

The Delineation of Deep Crustal Magnetic Bodies from Total Field Aeromagnetic Anomalies

Bhattacharyya

Morley

1965

J. geomagn. geoelec

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“…We use the notation of equation (10) in Bhattacharyya (1964). The fourth and the fifth terms in the R.H.S.…”

Section: Step 1: Extraction Of the Magnetic Field Originatingmentioning

confidence: 99%

“…We usually use the following formula introduced by Bhattacharyya (1964) for the analytical expression of the contribution of a magnetization prism to the magnetic total intensity anomaly:…”

Section: Step 1: Extraction Of the Magnetic Field Originatingmentioning

confidence: 99%

An aeromagnetic survey of Shinmoe-dake volcano, Kirishima, Japan, after the 2011 eruption using an unmanned autonomous helicopter

et al. 2013

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“…This forward calculation was based on the use of the methods by Bhattacharyya (1964) and its modified version by Kunaratnam (1981). We obtained J 0 , which minimised the above objective function as follows:…”

Section: Magnetic Field Anomalymentioning

confidence: 99%

Aeromagnetic survey using an unmanned autonomous helicopter over Tarumae Volcano, northern Japan

Hashimoto

Koyama

Kaneko

et al. 2014

Exploration Geophysics

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Unmanned aerial vehicles (UAVs) have recently drawn attention in various research fields for their ability to perform measurements, surveillance, and operations in hazardous areas. Our application is volcano surveillance, in which we used an unmanned autonomous helicopter to conduct a dense low-altitude aeromagnetic survey over Tarumae volcano, northern Japan.In autonomous flight, we demonstrated positioning control with an accuracy of approximately 10 m, which would be difficult for an ordinary crewed vehicle. In contrast to ground-based magnetic measurement, which is highly susceptible to local anomalies, the field gradient in the air with a terrain clearance of 100 to 300 m was fairly small at 1 nT/m. This result suggests that detection of temporal changes of an order of 10 nT may be feasible through a direct comparison of magnetic data between separate surveys by means of such a system, rather than that obtained by upward continuation to a common reduction surface. We assessed the temporal magnetic changes in the air, assuming the same remagnetising source within the volcano that was recently determined through ground surveys. We conclude that these expected temporal changes would reach a detection level in several years through a future survey in the air with the same autonomous vehicle.

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Magnetic Anomalies Due to Prism‐shaped Bodies With Arbitrary Polarization

Cited by 277 publications

References 0 publications

The Delineation of Deep Crustal Magnetic Bodies from Total Field Aeromagnetic Anomalies

The Delineation of Deep Crustal Magnetic Bodies from Total Field Aeromagnetic Anomalies

An aeromagnetic survey of Shinmoe-dake volcano, Kirishima, Japan, after the 2011 eruption using an unmanned autonomous helicopter

Aeromagnetic survey using an unmanned autonomous helicopter over Tarumae Volcano, northern Japan

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