Analysis of Magnetic Anomaly Characteristics of Underground Non-Coplanar Cross-buried Iron Pipelines

2020 ◽  
Vol 25 (2) ◽  
pp. 223-233
Author(s):  
Pan Wu ◽  
Minghui Wei
Keyword(s):  
Magnetic Susceptibility ◽  
Magnetic Anomaly ◽  
Magnetic Dipole ◽  
Geomagnetic Field ◽  
Magnetic Anomalies ◽  
Buried Pipelines ◽  
Magnetic Declination ◽  
Magnetic Inclination ◽  
Basic Characteristics ◽  
Geomagnetic Intensity

The non-coplanar cross-buried pipelines are a common way of pipeline wiring. In order to investigate the magnetic anomaly characteristics of the non-coplanar cross-buried pipelines and guide the site operation, the influences of a series of factors on the magnetic anomaly of the non-coplanar cross-buried pipelines are analyzed. Based on the principle of magnetic dipole construction, a forward model is established for the magnetic anomaly characteristics of the subsurface non-coplanar cross-buried pipelines. The basic characteristics of magnetic anomaly for the non-coplanar cross-buried pipelines are defined. The influences of geomagnetic parameters (geomagnetic intensity, geomagnetic inclination, and geomagnetic declination), pipeline parameters (thickness, magnetic susceptibility), and cross angle of pipelines on the characteristics of magnetic anomalies are analyzed. The results show that the shape of the total magnetic anomaly is mainly affected by the magnetic inclination, and the curve of magnetic anomaly at ± I site shows some symmetry. The amplitude is approximately linearly affected by the total geomagnetic field, magnetic declination, pipeline thickness, material magnetic susceptibility, and pipeline cross angle. There is a periodic change of the amplitude with the increase of geomagnetic inclination (−90°–>90°). The crest-trough distance is mainly affected by geomagnetic inclination, magnetic declination, thickness, magnetic susceptibility, and pipeline cross angle. A more accurate measurement can be achieved if the direction of the pipelines is roughly measured and then the number of measurement points is augmented near the intersection of pipelines and the measurement lines. Present work obtains the equivalent magnetic dipole units by segmenting pipelines. The magnetic anomaly characteristics of non-coplanar crossed iron pipelines are successfully simulated. The numerical results are in accordance with the experimental analysis.

Bird Migration Across a Strong Magnetic Anomaly

1987 ◽  
Vol 130 (1) ◽  
pp. 63-86 ◽  
Author(s):  
THOMAS ALERSTAM
Keyword(s):  
Magnetic Anomaly ◽  
Geomagnetic Field ◽  
Magnetic Field Intensity ◽  
Bird Migration ◽  
Height Loss ◽  
Magnetic Inclination ◽  
Low Altitude ◽  
Migrating Birds ◽  
The Magnetic Field ◽  
Visual Observations

Migratory flights of birds across a strong magnetic anomaly were recorded by tracking radar and, during the daytime, by simultaneous visual observations. The anomaly in central Sweden is about 12 km long and a few kilometres wide, with the total magnetic intensity at low altitude exceeding the normal field by up to 60%, according to aeromagnetic measurements. Migrants change altitude, most often by starting to descend, to a significantly greater extent over those parts of the anomaly where the magnetic field intensity is abnormally high, and particularly where the magnetic inclination is steepest, than over other parts of the study area and at another study area with a normal geomagnetic field. The descents lasted on average about 2 min, with a mean angle of descent of 2.6°, leading to a height loss of about 100 m before level flight was resumed. Flock formations were repeatedly broken up during these temporary descents. The changes in flight altitude were associated with gradients in magnetic inclination along the birds' flight paths across the anomaly. This supports the possibility that birds use the geomagnetic field and associated gradients for continuous guiding and recording of migration. Additional visual observations of migrating birds at the lowest altitudes over the magnetic anomaly suggest that birds sometimes become briefly disturbed (clear weather) or disoriented for longer periods, because of difficulties in finding their way out of the anomaly area (poor visibility).

QUANTITATIVE INTERPRETATION OF VERTICAL MAGNETIC ANOMALIES OVER VEINS

Geophysics ◽  
1950 ◽  
Vol 15 (4) ◽  
pp. 667-686 ◽  
Author(s):  
Kenneth L. Cook
Keyword(s):  
Magnetic Field ◽  
Magnetic Anomaly ◽  
Magnetic Induction ◽  
Vertical Component ◽  
Magnetic Anomalies ◽  
Quantitative Interpretation ◽  
Magnetic Intensity ◽  
Magnetic Inclination ◽  
Magnetic North ◽  
The Magnetic Field

By using ordinary magnetic induction methods of analysis, Haalck, Heiland, and others have developed formulas which express the magnetic anomaly over a vertical or inclined vein of tabular shape as a function of the susceptibility, dimensions, shape, and disposition of the vein, and of the strength and direction of the earth’s magnetic field. On the basis of these fundamental formulas, other formulas for the vertical component of the magnetic field are derived in the present paper for such veins in intermediate northern magnetic latitudes. Special emphasis is given to the orientation of the veins relative to the magnetic north direction. Several families of vertical magnetic intensity curves for veins with different strikes and dips are given. All theoretical curves for veins striking magnetic north are plotted in terms of a parametric unit so that, once plotted, they can be used repeatedly in different districts, provided a proper multiplying factor is chosen for the observed curve. The importance of the transverse horizontal magnetization effect under certain conditions of orientation is demonstrated. It is shown mathematically that small vertical magnetic anomalies are to be expected for thin veins striking east and dipping south at an angle equal to, or approximately equal to, the complement of the angle of magnetic inclination.

scholarly journals Distribution of Iron Sand in The Widarapayung Coast Area at Regency of Cilacap Based on Magnetic Anomaly Data

2017 ◽  
Vol 6 (02) ◽  
pp. 97
Author(s):  
Sehah Allasimy ◽  
Sukmaji Anom Raharjo ◽  
Muhammad Andi Kurniawan
Keyword(s):  
Magnetic Susceptibility ◽  
Magnetic Anomaly ◽  
Magnetic Anomalies ◽  
Research Area ◽  
Object Model ◽  
Intensity Data ◽  
Magnetic Intensity ◽  
A Value ◽  
Proton Precession Magnetometer ◽  
Sand And Gravel

Interpretation on the magnetic anomalies data has been done in the Widarapayung coast area, District of Binangun, Regency of Cilacap to identify distribution of iron sand. The acquisition of magnetic intensity data in this area has been done in December 2015 and May 2016 using Proton Precession Magnetometer (PPM) with type of GSM-19T. The research area extends on the geographic positions of 109.2501°BT – 109.2702°E and 7.6781°LS – 7.6986°S. Magnetic anomalies data modeling is done with using Mag2DC for Windows software so obtained some subsurface anomalous objects model. The anomaly object model having a value of magnetic susceptibility of 0.0093cgs unit is interpreted as iron sand interspersed with silt, clay, sand, and gravel from the alluvium formation. This formation is lain at a depth of 1.709 to 11.966m and a length of 1576.7m. The iron sand contained in this formation is estimated prospects for exploitation. Based on the interpretation results, alluvium formation is also found at a depth of 1.140 to 30.769m, which expected be composed of silt, clay, sand, and gravel with a magnetic susceptibility value of 0.0051cgs unit. The content of iron sand in this 2<sup>nd</sup> alluvium formation is expected to be relatively small.

Interpretation of magnetic anomalies due to dikes: The complex gradient method

Geophysics ◽  
1981 ◽  
Vol 46 (11) ◽  
pp. 1572-1578 ◽  
Author(s):  
D. Atchuta Rao ◽  
H. V. Ram Babu ◽  
P. V. Sanker Narayan
Keyword(s):  
Magnetic Anomaly ◽  
Magnetic Anomalies ◽  
Half Width ◽  
Amplitude Function ◽  
Maximum Value ◽  
Magnetic Inclination ◽  
Vector Quantity ◽  
Characteristic Points ◽  
Depth Of Burial ◽  
Complex Gradient

A method to interpret the magnetic anomaly due to a dipping dike using the resultant of the horizontal and vertical gradients of the anomaly is suggested. The resultant of both the gradients is a vector quantity and is defined as the “complex gradient.” A few characteristic points defined on the amplitude and phase plots of the complex gradient are used to solve for the parameters of the dike. For a dike uniformly magnetized in the earth’s magnetic field, the amplitude plot is independent of [Formula: see text], the index parameter, which depends upon the strike and dip of the dike and the magnetic inclination of the area. The phase plot of the complex gradient is an antisymmetric curve with an offset value equal to [Formula: see text]. For a dike whose half‐width is greater than its depth of burial, two maxima at equal distances on either side of a minimum value appear on the amplitude plot. For a dike whose half‐width is equal to or less than its depth of burial, the amplitude plot is a bell‐shaped symmetric curve with its maximum appearing directly over the origin. In the case of a thin dike, the amplitude function falls off to half its maximum value at the same point on the abscissa where the phase function reaches, i.e., [Formula: see text]. A combined analysis of the amplitude and phase plots of the complex gradient yields all the parameters of the dike. The method is applicable for the magnetic anomaly in either the total, vertical, or horizontal field. A field example is included to show the applicability of the method.

scholarly journals Report on the magnetic survey in Slovakia for the 2014.5 epoch

2016 ◽  
Vol 46 (1) ◽  
pp. 51-60
Author(s):  
Fridrich Valach ◽  
Magdaléna Váczyová ◽  
Tomáš Šoltis ◽  
Melinda Vajkai
Keyword(s):  
Secular Variation ◽  
Geomagnetic Field ◽  
Polynomial Model ◽  
Magnetic Survey ◽  
Total Field ◽  
Degree Polynomial ◽  
Magnetic Declination ◽  
Geomagnetic Survey ◽  
Magnetic Inclination ◽  
Geomagnetic Measurements

Abstract The models of the distribution of the elements of the geomagnetic field must be updated regularly. For this purpose geomagnetic measurements have to be carried out repeatedly at geomagnetic observatories as well as at temporary observation points. In this paper the results of the geomagnetic survey that was carried out in Slovakia in the year 2014 are presented. The measurements were performed at 12 observation points and they were reduced to the 2014.5 epoch. The secular variation between 2007.5 and 2014.5 was also calculated. The obtained values of the geomagnetic elements were used for calculating a 1st-degree polynomial model for the distribution of magnetic declination, inclination and total field. The comparison with the IGRF model showed that the polynomial model provided more accurate results for magnetic inclination and total field. For magnetic declination, on the contrary, the IGRF model produced slightly better results than the polynomial model.

scholarly journals Estimasi Kedalaman Bitumen Batubara di Desa Banjaran Kecamatan Salem Kabupaten Brebes Berdasarkan Data Anomali Magnetik

2017 ◽  
Vol 4 (02) ◽  
pp. 171
Author(s):  
Sehah S ◽  
Sukmaji Anom Raharjo ◽  
Adi Chandra
Keyword(s):  
Magnetic Susceptibility ◽  
Data Processing ◽  
Data Acquisition ◽  
Magnetic Anomaly ◽  
Field Data ◽  
Magnetic Anomalies ◽  
Research Area ◽  
Magnetic Data ◽  
Geological Information ◽  
The Village

<p>The Estimation of coal bituminous depth in Village of Banjaran, District of Salem, Regency of Brebes based on magnetic anomaly data has been done. The Village of Banjaran is located in the geology basin which called as Bentarsari Basin. The activities stages that carried out in this research include of magnetic data acquisition in the field, data processing, and interpretation. The interpretation of the anomalies data is done through the modeling using the Mag2DC for Window software on the local magnetic anomalies data. Based on this modeling results, then obtained six anomalous objects that can be interpreted as the subsurface rocks in the research area, which consists of sediments of gravel, sand, clay, and silt ( = 0.0020 cgs units); tuff and tuffaceous sandstone ( = 0.0069cgs units); andesite breccia, tuff, and tuffaceous sandstone ( = 0.0085cgs units); solid andesite breccia which not layered ( = 0.0115 cgs units); coarse sandstones, limestones, and sandy marl ( = 0.0109cgs units); andesite sandstone that layered with claystone and thin insertions of new coal bituminous alternately ( = 0.0008cgs units). Based on the modeling results and the geological information of this research area, it can be estimated that the coal bituminous found in the Kaliglagah formation, with its depths ranging between 104.48 m – 505.97m, and the value of the magnetic susceptibility is 0.0008 cgs units.</p>

scholarly journals Measurements of vector magnetic anomalies on board the icebreaker Shirase and the magnetization of the ship

1999 ◽  
Vol 42 (2) ◽  
Author(s):  
Y. Nogi ◽  
K. Kaminuma
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Field ◽  
Magnetic Anomalies ◽  
The Other ◽  
South Indian Ocean ◽  
Permanent Magnetic Field ◽  
South Indian ◽  
Antarctic Research ◽  
Permanent Magnetization ◽  
Made In

Vector measurements of the geomagnetic field have been made in the South Indian Ocean since 1988 when a Shipboard Three Component Magnetometer (STCM) was installed on board the icebreaker Shirase by the 30th Japanese Antarctic Research Expedition (JARE-30). Twelve constants related to the ship's induced and permanent magnetic field were determined by the data obtained from the JARE-30 to the JARE-35. The constants related to the ship's magnetic susceptibility distribution are almost stable throughout the cruise and mostly depend on the ship's shape. On the other hand, the constants related to the ship's permanent magnetization are variable. However, absolute values of total intensity geomagnetic field calculated from vector geomagnetic field is possible to use, if the constraints from total intensity geomagnetic field measured by the proton magnetometer and/or satellite derived magnetic anomalies are applied.

scholarly journals A tectonomagnetic effect detected in Central Italy

1994 ◽  
Vol 37 (1) ◽  
Author(s):  
G. Mele ◽  
A. Meloni ◽  
P. Palangio
Keyword(s):  
Field Intensity ◽  
Geomagnetic Field ◽  
Central Italy ◽  
Volcanic Eruptions ◽  
Intensity Data ◽  
Absolute Level ◽  
Tectonic Events ◽  
Railway System ◽  
The Absolute ◽  
Geomagnetic Intensity

Significant variations in the absolute value of the geomagnetic field intensity related to tectonic events, as earthquakes and volcanic eruptions, have been observed in several cases. To detect such a tectonomagnetic effect related to seismic activity, a seismomagnetic network was installed by the Istituto Nazionale di Geofisica (ING) in the Abruzzi region (CentraI Italy), in July 1989. This area is being uplifting since the Pliocene. A logistic compromise between geophysical requirements and the electrified railway system tracks distribution led to the installation of five total magnetic field intensity data acquisition sites. From July 1989 to September 1992 geomagnetic intensity data were simultaneously recorded at all stations and compared to that recorded at the L'Aquila Observatory, located in the same area. A variation of about 10 nT in the absolute level of the geomagnetic field was measured at two stations located on the eastern side of the network. We suggest that the detected magnetic anomaly could resuIt from aseismic-changes in crustal stress during this time.

scholarly journals Magnetic anomaly inversion using magnetic dipole reconstruction based on the pipeline section segmentation method

2016 ◽  
Vol 13 (3) ◽  
pp. 242-258 ◽  
Author(s):  
Qi Pan ◽  
De-Jun Liu ◽  
Zhi-Yong Guo ◽  
Hua-Feng Fang ◽  
Mu-Qun Feng
Keyword(s):  
Magnetic Anomaly ◽  
Magnetic Dipole ◽  
Segmentation Method ◽  
Pipeline Section

Using airborne vector magnetic data to calculate the projection of magnetic anomaly vector onto normal geomagnetic field

Geophysics ◽  
2021 ◽  
pp. 1-47
Author(s):  
Rukuan Xie ◽  
Shengqing Xiong ◽  
Shuling Duan ◽  
Jinlong Wang ◽  
Ping Wang ◽  
...  
Keyword(s):  
Magnetic Anomaly ◽  
Geomagnetic Field ◽  
Approximation Error ◽  
Magnetic Data ◽  
Total Field ◽  
Projection Formula ◽  
Total Magnetization ◽  
Vector Formula ◽  
Relationship Of ◽  
Anomaly Formula

The total-field magnetic anomaly [Formula: see text] is an approximation of the projection [Formula: see text] of the magnetic anomaly vector [Formula: see text] onto the normal geomagnetic field [Formula: see text]. However, for highly magnetic sources, the approximation error of [Formula: see text] cannot be ignored. To reduce the error, we have developed a method for calculating [Formula: see text] by using airborne vector magnetic data based on the vector relationship of geomagnetic field [Formula: see text]. The calculation uses the magnitude of the vectors [Formula: see text], [Formula: see text], and [Formula: see text] through a simple approach. To ensure that each magnitude has the same level, we normalize the magnitude of [Formula: see text] using the total-field magnetic data measured by the scalar magnetic sensor. The method is applied to the measured airborne vector magnetic data at the Qixin area of the East Tianshan Mountains in China. The results indicate that the calculated [Formula: see text] has high precision and can distinguish the approximation error less than 3.5 nT. We also analyze the characteristics of the approximation error that are caused by the effects of different total magnetization inclinations. These error characteristics are used to predict the total magnetization inclination of a 2D magnetic source based on the measured airborne vector magnetic data.

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