Geomagnetism: Earth’s magnetic field Dipole Field.

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Presentation transcript:

Geomagnetism: Earth’s magnetic field Dipole Field

Strength of Earth’s magnetic field (nT)

Higher order poles

Power spectrum of Earth’s magnetic field

Inclination of Earth’s magnetic field

Inclination and Declination Inclination is related to latitude Declination depends on horizontal components

Declination of Earth’s magnetic field

Magnetic North Pole vs. time

Magnetic vs. Geographic coordinates Dipole drifts westward at: °/century ( yr period) Non-dipole features drift westward at: 0.2 – 0.7°/century ( yr period)

Geomagnetic field strength is decreasing: Will fall to zero in the year 4000: The beginning of a reversal?

Paleomagnetism: Study of geomagnetic field vs. time Spinner magnetometer Astatic magnetometer Cryogenic magnetometer

Axial Geocentric Dipole Hypothesis:average over 10 4 years is geographic pole tan I = 2 tan λ Plio-Pleistocene paleomag poles

Calculating a paleomagnetic pole

Baked contact test

Reversals Test

Apparent Polar Wander paths

Paleo Reconstructions

Magnetic Reversals

Magnetic Reversals vs. Time

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