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Watch video lecture on YouTube: Geomagnetism - 3 Process and Causes; Paleomagnetism

Geomagnetism - 3 Process and Causes; Paleomagnetism

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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.

Geomagnetism Image

Geomagnetism Image

Geomagnetism Image

Terminology

  • Geomagnetic Pole

  • Magnetic Pole

  • Geographic Pole

Earth’s Actual Magnetic Field

Earth’s Actual Magnetic Field Image-1

Earth’S Actual Magnetic Field Image-1

Earth’s Actual Magnetic Field Image-1

Earth’s Actual Magnetic Field Image-2

Earth’S Actual Magnetic Field Image-2

Earth’s Actual Magnetic Field Image-2

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

Declination & Inclination Image-1

Declination & Inclination Image-1

Declination & Inclination Image-1

Magnetic Declination - Isogonic

Magnetic Declination - Isogonic Image

Magnetic Declination - Isogonic Image

Magnetic Declination - Isogonic Image

Magnetic Inclination or Dip - Isoclinic

Magnetic Inclination or Dip - Isoclinic Image-1

Magnetic Inclination or Dip - Isoclinic Image-1

Magnetic Inclination or Dip - Isoclinic Image-1

Magnetic Inclination or Dip - Isoclinic Image-2

Magnetic Inclination or Dip - Isoclinic Image-2

Magnetic Inclination or Dip - Isoclinic Image-2

Paleomagnetism

  • Polar Wandering & Continental Drift

  • Remanent Magnetization

    • Thermal

    • Detrital

    • Chemical

Magnetic Field Detection

  • Magnetometers

  • Satellites

  • Geomagnetic Observatories

  • Magnetic Anomaly Detectors

  • Animals

  • Seismo-Electromagnetics