LIMITING VALUES OF GRAVITATIONAL AND MAGNETIC ANOMALIES DUE TO A SUBTERRANEAN STRUCTURE BOUNDED BY A SINGLE DIFFERENTIAL SURFACE

Geophysics ◽  
1941 ◽  
Vol 6 (1) ◽  
pp. 1-12 ◽  
Author(s):  
J. W. Fisher
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Magnetic Anomalies ◽  
Effective Thickness ◽  
Earth’S Magnetic Field ◽  
Magnetic Effects ◽  
Earth's Magnetic Field ◽  
Survey Results ◽  
Limiting Values

Calculations are made of gravitational and magnetic anomalies supposed due to local variations in the form of a single differential surface separating an overlying rock from an underlying one, the effective thickness of the latter being infinite. Both layers are homogeneous in density or magnetic susceptibility and only those magnetic effects are considered which are due to induction in the earth’s magnetic field. The maximum possible values of these anomalies and of their first and second horizontal derivatives are calculated under these simplified conditions, and it is pointed out that the numerical readings of these quantities, provided by survey results, may lead to useful estimates of the extreme depth and proportions of the structure responsible.

Broad-scale magnetic anomalies over central and eastern Canada: a discussion

1981 ◽  
Vol 18 (3) ◽  
pp. 657-661 ◽  
Author(s):  
R. L. Coles ◽  
G. V. Haines ◽  
W. Hannaford
Keyword(s):  
Magnetic Field ◽  
Sea Level ◽  
Vertical Component ◽  
Magnetic Anomalies ◽  
Superior Province ◽  
The South ◽  
Earth’S Magnetic Field ◽  
Eastern Canada ◽  
Earth's Magnetic Field ◽  
Broad Scale

Profiles of anomalies in the vertical component of the Earth's magnetic field over central and eastern Canada, observed at an average altitude of 4 km above sea level, show broad regions with distinctive anomaly character. These subdivisions indicate major differences in the evolutions of regions within individual structural provinces. Particularly notable is a region of intense anomalies in the northern part of the Superior Province in Quebec, contrasting with much weaker anomaly relief to the south and east.

scholarly journals The bioenergetic resonance model at pre-sowing seed crops treatment

2021 ◽  
pp. 97-106
Author(s):  
A. Kushnirenko ◽  
◽  
V. Pryadko ◽  
O. Sinyavsky ◽  
◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Magnetic Resonance ◽  
Constant Magnetic Field ◽  
Unit Volume ◽  
Magnetization Vector ◽  
Alternating Magnetic Field ◽  
Agricultural Crops ◽  
Earth’S Magnetic Field ◽  
Earth's Magnetic Field

The research is devoted to the study of the behavior of the generalizing magnetization vector in the seeds of agricultural crops under the action of longitudinal constant and transverse alternating magnetic fields by the method of nuclear magnetic resonance. Based on the theoretical studies, the value of the average magnetic susceptibility per unit volume of seed χ and the value of the magnetization vector were determined. For the system of microparticles of cells of plant origin, the average magnetic susceptibility per unit volume of seed is χ = 2.1 · 10-5, and the magnetization vector M=13.125 mA/m at a longitudinal constant magnetic field strength H = 625 A/m. When a weak transverse alternating magnetic field is superimposed on the frequency, the oscillation frequencies of the magnetization vectors M coincide with the field frequency, which is a condition for the occurrence of magnetic resonance. The longitudinal magnetization vector during the transition from the ground state to the excited state (resonant) describes a trajectory in the form of a spiral on the surface of the sphere. A mathematical model for a biological system taking into account the Earth's magnetic field is built. It is established that for the technology of pre-sowing treatment of seeds of agricultural crops, the inductor, which creates a constant magnetic field, must be located so that the vector of the constant magnetic field of the inductor coincides with the vector of the Earth's magnetic field. Keywords: bioenergetic resonance, pre-sowing treatment of crop seeds, direct magnetic field, alternating magnetic field, longitudinal and transverse relaxation

Pigeons at Magnetic Anomalies: The Effects of Loft Location

1992 ◽  
Vol 170 (1) ◽  
pp. 127-141 ◽  
Author(s):  
CHARLES WALCOTT
Keyword(s):  
Magnetic Field ◽  
Magnetic Anomaly ◽  
Magnetic Anomalies ◽  
Earth’S Magnetic Field ◽  
Homing Pigeons ◽  
Magnetic Gradient ◽  
Earth's Magnetic Field

Homing pigeons from our old lofts at Fox Ridge Farm in Lincoln, MA, were disoriented when released at places where the earth's magnetic field was irregular-so-called ‘magnetic anomalies’. The orientation of pigeons raised in our lofts at Cornell in Ithaca, NY, was unaffected by anomalies. Further experiments in Lincoln showed that sibling pigeons raised and trained to lofts only 2.5 km apart behaved differently when released at a strong magnetic anomaly. Pigeons from the loft situated in a magnetic gradient of 450 nT km−1 were disoriented at anomalies, whereas birds raised in a loft in a magnetic gradient of 88nT km−1 were well oriented. This suggests that the location of the home loft may play an important role in determining which cues pigeons use for their navigation, and that these cues are learned sometime after weaning from their parents at 4–6 weeks after hatching.

7. The Earth’s magnetic field

2018 ◽  
pp. 106-126
Author(s):  
William Lowrie
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Field ◽  
Plate Tectonics ◽  
Magnetic Anomalies ◽  
Earth’S Magnetic Field ◽  
The Earth ◽  
Earth's Magnetic Field ◽  
Reversed Polarity ◽  
Harmful Radiation ◽  
The Magnetic Field

The Earth is surrounded by a magnetic field, which originates inside its molten core, and which for centuries has helped travellers to navigate safely across uncharted regions. The magnetic field protects life on the Earth by acting as a shield against harmful radiation from space, especially from the Sun. ‘The Earth’s magnetic field’ explains that the magnetic field at the Earth’s surface is dominantly that of an inclined dipole. The Sun’s deforming effect on the magnetic field outside the Earth is described, as are the magnetic fields of other planets. The magnetism of rocks forms the basis of palaeomagnetism, which explains how plate tectonics displaced the continents and produced oceanic magnetic anomalies whenever the geomagnetic field reversed polarity.

scholarly journals NEW INTERPRETATION OF THE EARTH’S MAGNETIC FIELD EFFECTS’ ON LIFE

2020 ◽  
Vol 53 (2C) ◽  
pp. 13-25
Author(s):  
Basim Hijab
Keyword(s):  
Magnetic Field ◽  
Influenza Pandemic ◽  
Magnetic Anomalies ◽  
Magnetic Field Effects ◽  
Earth’S Magnetic Field ◽  
The Past ◽  
Earth's Magnetic Field ◽  
New Interpretation ◽  
Influenza Outbreaks ◽  
Clear Relation

The relationships of the Earth’s magnetic field intensity and time (the past 320 years) for many locations around the world are obtained, based on the IGRF-13 mathematical model. The results showed that each location on the earth surface has its magnetic intensity relation with time that reflects local variations. The sudden changes (magnetic anomalies) in the Earth’s magnetic field with time are natural phenomena, which are different from place to another. These magnetic anomalies are investigated for possible relationship to the historical records of the influenza pandemic outbreaks. The results showed clear congruences between the Earth’s magnetic anomalies and influenza outbreaks times. The congruences become clearer when comparing the highest magnetic anomaly intensity and the first outbreak location of the influenza pandemic. This is true for the recorded historical data since 1890 AD. It is not known how the changes in Earth’s magnetic field affect the virus’s outbreaks or evolution, but there is a clear relation that needs detailed studies.

scholarly journals MEASUREMENT AND EVALUATION OF THE EARTH'S MAGNETIC FIELD BY MEANS OF THE SMALL SPACECRAFT ECUADOR-UTE (HC1PX

2021 ◽  
pp. 1-6
Author(s):  
Aleksey Schitov ◽  
Oleg Dobroserdov ◽  
Sergey Frolov ◽  
Ludmila Semenova
Keyword(s):  
Magnetic Field ◽  
Oil And Gas ◽  
Magnetic Anomalies ◽  
Earth’S Magnetic Field ◽  
Tectonic Structures ◽  
Small Spacecraft ◽  
Measurement Results ◽  
Earth's Magnetic Field ◽  
Magnetic Tension ◽  
Measurement And Evaluation

The paper deals with the use of the small spacecraft ECUADOR-UTE (HC1PX) designed to conduct space experiments in autonomous flight conditions and, in particular, to measure the Earth’s electromagnetic field and study the ionosphere. The spacecraft has a built-in target load module, including a precision magnetometer that measures the Earth’s magnetic field. The measurement results are used to study the properties and state of the circumterranean environment including magnetic anomalies. The latter may indicate certain tectonic structures in the sedimentary stratum, which are indicators of oil and gas, and magnetic pole displacement processes. Measurement results can also be used for prediction and forecasting efforts in anomalouszones. The compiled analytical dependences for the anomalous zones can serve as a forecasting device when studying the magnetic tension of the Earth’s geographic regions by means of a spacecraft. Measuring the magnetic anomalies of the Earth’s surface is should prove necessary forfactoring them in and developingnational industries.

Magnetic effects of a finite, arbitrarily oriented line of dipoles

Geophysics ◽  
1991 ◽  
Vol 56 (9) ◽  
pp. 1474-1476
Author(s):  
Birendra K. Jain
Keyword(s):  
Magnetic Field ◽  
Closed Form ◽  
Magnetic Data ◽  
Important Class ◽  
Earth’S Magnetic Field ◽  
Magnetic Effects ◽  
Oriented Line ◽  
Earth's Magnetic Field ◽  
Finite Line ◽  
Limited Depth

Lines of dipoles are an important class of 3-D theoretical bodies and are often used to model the effects due to narrow, elongated magnetic bodies of limited depth extents in the interpretation of magnetic data. The application includes geologic bodies such as mineralized veins and pipes, as well as nongeologic bodies such as well casings. Though closed‐form expressions for the magnetic effects of such a finite line of dipoles are available in the published literature, the cases treated are quite restricted, i.e., the expressions are given for the line either parallel or perpendicular to the plane of observation (e.g., Nettleton, 1942, Hall, 1959, Singh and Sabina, 1978) or for the line inductively magnetized and dipping in the direction of the earth’s magnetic field (e.g., Henderson and Zeitz, 1967).

Remanent Magnetism and Beaker Chronology

Antiquity ◽  
1962 ◽  
Vol 36 (143) ◽  
pp. 206-209 ◽  
Author(s):  
D. L. Clarke ◽  
G. Connah
Keyword(s):  
Magnetic Field ◽  
Magnetic Anomalies ◽  
Vertical Position ◽  
Relative Order ◽  
Earth’S Magnetic Field ◽  
Important Work ◽  
Remanent Magnetism ◽  
Relative Chronology ◽  
Magnetic Elements ◽  
Earth's Magnetic Field

Recent work on Archaeomagnetism has been concentrated in two main fields, first, detection of sites with magnetic anomalies using instruments like the proton magnetometer, and secondly the construction of a dated graph of the earth’s magnetic field with the ultimate aim of providing an absolute chronology for fixed fired sites, mainly kilns and hearths. Important work in a third field, using the changing angle of inclination of pottery to provide a relative chronology for a series of vessels entirely independent of archaeological means, has fallen out of fashion despite the efforts of the pioneers of Archaeomagnetism and more recently the researches of Mr R. M. Cook on Corinthian pottery, at Cambridge and Dr M. J. Aitken on Chinese porcelain at Oxford. It is with this third method of approach that the present article is concerned and its application to a series of British beakers.When a clay vessel is fired its temperature is usually raised well above the Curie-point, about 500-600° C.; at this point the magnetic elements in the clay will begin to orientate themselves with the prevailing Earth’s magnetic field rather as though they were myriads of minute compass needles. Upon cooling, this uniform orientation will remain ‘fossilized’ and under normal conditions a permanent record of the Earth’s magnetic field at the time and place of firing. However, the finished vessel will then be used and removed from its firing position, thus for ever removing any chance of comparing its angle of declination (or compass bearing) with that now existing, since their positions relative to geographic north cannot be determined. If it can be shown that the vessel was fired in a vertical position the angle of inclination (dip) is still recoverable for comparison with the modern angle and with that preserved in other similar vessels. Since the angle of inclination alters a little every year (non-linearly)—it should be theoretically possible to arrange them in relative order of firing or date, thus providing an invaluable relative chronology.

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