Here’s a breakdown of the provided text, focusing on the key information about Earth’s magnetic field reversals:
What are Magnetic Reversals?
Earth’s magnetic field is generated by the movement of liquid metals in its outer core.
This movement causes the magnetic poles to shift over time.
A magnetic reversal is when the earth’s magnetic north and south poles swap places.
Key Events and Concepts:
Brunhes-Matuyama Reversal: The last “true” sustained reversal, occurring around 780,000 years ago.It’s named after the geophysicists who discovered it.
Laschamp Event: A shorter-lived reversal that happened around 42,000 years ago. The text notes that its temperature evidence from ice cores doesn’t align well with other data.
Duration of Reversals: The Brunhes-Matuyama reversal is believed to have taken longer than the Laschamp event, with some estimates suggesting it lasted up to 22,000 years.
Evidence: Paleomagnetic data from sediment drill cores globally is used to reconstruct past magnetic field behavior.
During a Reversal:
The magnetic field can weaken significantly, potentially to as little as 10% of its normal strength.
Multiple magnetic poles can appear, even at the equator.
Current Magnetic North Pole Movement:
The magnetic north pole has been moving, historically around Canada.
In recent decades,it accelerated towards Siberia.
However,in the last five years,its speed has decelerated significantly (from 50 to 35 km per year),which is an unprecedented observation.
Scientific Modeling and Visualization:
Researchers at the Helmholtz Center for Geosciences (GFZ) in Potsdam, Germany, have created a global model of the magnetic field before, during, and after reversals using paleomagnetic data.
This data has been visualized in a video that also uses a musical piece (three violins and three cellos) to represent the field’s evolution, with a “disharmonic cacophony” during the reversal.
Uncertainty:
While the poles are constantly moving, it’s still difficult to predict when the next true magnetic reversal will occur.
