GWP - MAGNETOMETRY

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MAGNETOMETRY

Typical Magnetic Raising

Objective: Get information associated to geological formations by means of the magnetic characteristics of the rocks.

A) Fields Phase
Defining a mesh and in every node to measure the magnetic Total field T and its projections H and Z (Horizontal and Vertical).
NOTE: in the South Hemisphere Z points up.

B) Office Phase
- Drawing isolines of Z and H vectors.


Isolines of Z and H vectors

INTERPRETATION
- The orientation of the H vectors allows to situate the ends of the dipole
- To chart T along a profile also allows to delimit the magnetic body ("Leaning Profile")
- To chart simultaneously H and Z along a profile allows to know the dipole slope
- The Z chart along a profile allows to know the dipole depth
- Suggested interpretation program: Magix XL

During the interpretation it's important to remember that according to one of Maxwell's Equations, the magnetic monopoles doesn't exist. In other words, the T leaning profile will always show two maximun (S Pole and N Pole).
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A magnetic prospection may determine:
* Magnetic minerals
* Hydrocarbures
* Space disposition of the dipole
* Geologic fractures
Magnitude order of the anomaly:
* Magnetite, hematite and pyrrhotite ~ 104 g
* Semimagnetic association ~ 103 g
* Hydrocarbure traps ~ 102 g

(Note: The poles position changes in the time)

The Future of the Magnetic Terrestrial Field (MTF)

Certain processes that happen inside the Earth cause that the MTF swings slowly: its magnitude weakens to get vanish and the reinforces an inverse sense. The process needs 700 thousand years, a fact that was probed by the "anomalous orientation" (in nowadays terms) of the magnetic minerals previous to the Pleistocene (once the matrix was solidified, the magnetic north of these minerals was pointing to the geographic south of the Earth (opposite to what happens today).

In the lapsus of 300 years the MTF has diminished a 15%. By extrapolation, the following annulment is going to be in the 40th century. In absence of the MTF, the compasses will not work and Van Allen's atmospheric belt (that protect us from cosmic radiation = mutagenic agent) will disappear. Curiously 700 thousands years ago, the first hominids appeared "explosively". Do we have to thank our existence to the MTF oscillation?

April, 2011

The Earth's magnetic poles are displaced and forced to adjust shipping routes
The magnetic north pole is moving more rapidly: 40 km per year from Canada. It is expected that in 50 years is located in Siberia.
By Alexis de Ponson

Each day, the north is 100 meters away from the North Pole. This data, provided by the Geological Survey of Canada, plot movement that is experiencing the magnetic north on the North Pole. The first is determined by the electromagnetic field of the Earth itself and the site to where compasses point, while the second corresponds to a geographical point, the man chosen to identify the location of the cardinal points.
The magnetic north pole is located in the northwestern part of Canada, and from 1972 to 2001 had moved the same distance as in the previous 140 years since its discovery in 1831. The Canadian agency now indicates that the north magnetic pole moves 40 miles per year and to continue this pace in 50 years will be in Siberia, Russia.
The phenomenon has forced aviation authorities to correct the orientation of the airstrips in relation to the new magnetic north pointing to the navigation instruments, as such information is crucial to organize air traffic. For instance, Tampa International Airport, Florida, United States, ended in February this process, for which it had to close for a month its tracks for takeoff and landing ships. "Everything has been changed, which was a great job," he told Discovery News Brenda Geoghagan spokesman terminal.
According to the report, every five years the Federal Aviation Administration assesses the orientation of its runways to make adjustments as necessary. The airports in Fort Lauderdale and Palm Beach, also located in Florida, have suffered the same process, which has not been without Chile.
The Directorate General of Civil Aviation (DGAC) said that for a while and every five years, are part of the American Aviation Authority software that serves as reference to make the necessary corrections to the Chilean courts. This information is supplemented with field data collection, traffic analysis and laboratory screening.
In 2010, the Administrator made the last update, which will remain in effect until 2015. The last track was corrected Diego Aracena Airport, Iquique.

An internal process
The origin of this phenomenon lies in the depths of the earth. Francisco Fuentes, geologist and professor at the Andrés Bello University, said that the most accepted hypothesis to explain the movement of magnetic north is the activity that occurs in the Earth's core, composed of a mixture of various metals in liquid state, including iron and nickel. "The currents that occur naturally in the Earth's core produce changes in the Earth's electromagnetic field," he says, adding that the magnitude of this effect depends on the amount of incandescent material moves inside the nucleus by these currents .
What would be causing this increased movement of material? It is not known. Some experts believe this could be the first step of the magnetic reversal process that takes 10 thousand years and in which the Earth's magnetic poles are reversed. A phenomenon that occurred 780,000 years ago and which scientists are unaware of their consequences.
It's not all: along with serving as a letter of sea and air, the electromagnetic field is essential to protect the Earth from solar winds that whip, so that some experts believe the change in the location of magnetic north could leave the Earth more exposed to solar radiation.

 
   
MYSTERY:
How can be detected an underground magnetic dipole?