Geomagnetim YouTube Lecture Handouts
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Geomagnetism - 3 Process and Causes; Paleomagnetism
Geomagnetism
The concept of geographic pole, geomagnetic pole and magnetic pole are explained by Dr. Manishika Jain in this lecture. Later on the concept of paleomagnetism and polar wandering are also introduced in this lecture.
Terminology
- Geomagnetic Pole
- Magnetic Pole
- Geographic Pole
Earth՚s Actual Magnetic Field
Cause of Earth՚s Geomagnetic Field
- Generated by fluid motions in the liquid, outer part of the Earth՚s core composed of iron.
- Driven by buoyancy forces formed at the base of the outer core as Earth cools and iron condenses onto the solid, inner solid core below.
- Rotation causes buoyant fluid to rise in curved trajectories (Coriolis force) generating magnetic field
- Basic structure is a simple north-south field.
- Dipole aligned closely with the Earth՚s rotation axis
- Magnetic poles are usually close to the geographic poles
- Occasionally dipole field reverses
- Seen in the paleomagnetic record in rocks of the ocean floor and lava flows
- Reversal process not periodic
- 10,000 years to 25 million years
- Smaller, non-dipolar structures change locally and very slightly on a century timescale.
Declination & Inclination
Magnetic Declination - Isogonic
Magnetic Inclination or Dip - Isoclinic
Paleomagnetism
- Polar Wandering & Continental Drift
- Remanent Magnetization
- Thermal
- Detrital
- Chemical
Magnetic Field Detection
- Magnetometers
- Satellites
- Geomagnetic Observatories
- Magnetic Anomaly Detectors
- Animals
- Seismo-Electromagnetics
✍ Manishika