Japanese Researchers Identify Two Stable Polarity States in Breakthrough Earth Magnetic Field Simulation

Researchers at NIFS use supercomputers to show how Earth's magnetic poles maintain stability and what might trigger the next irregular polarity reversal.

By: AXL Media

Published: Apr 24, 2026, 6:36 AM EDT

Source: Information for this report was sourced from EurekAlert!

A Quarter Century of Unsolved Magnetic Mysteries

While scientists have long understood that the Earth behaves as a giant magnet, the specific physical triggers behind the irregular reversal of its magnetic poles have remained elusive. Albert Einstein famously categorized the origin of the Earth magnetic field as a primary unsolved scientific problem, specifically regarding how liquid iron convection in the outer core sustains this field. According to the National Institute for Fusion Science, paleomagnetism studies confirm that these polarity flips occur at unpredictable intervals ranging from hundreds of thousands to millions of years. Despite previous simulations successfully reproducing the aperiodic nature of these flips, the underlying mechanism that actually forces the stable dipole to break and reverse has stayed hidden from researchers for decades.

Simulating the Core Using Advanced Computing Power

In a recent collaborative effort, researchers from SOKENDAI and the National Institute for Fusion Science employed the Raijin and Sosei supercomputers to conduct three-dimensional magnetohydrodynamic simulations. Led by Assistant Professor Hiroki Hasegawa and Associate Professor Hiroaki Ohtani, the team applied a Yin-Yang grid system to model the spherical-shell geometry of the Earth outer core. By introducing fifty different random weak magnetic perturbations into a simplified convective environment, the researchers observed how various initial conditions influenced the final state of the magnetic field. This computational approach allowed the team to isolate the impact of initial fluctuations from the influence of background convection.

The Probability of North and South Polarity

The results of the simulation revealed that every trial eventually evolved into a dominant dipole magnetic field, with northward and southward polarities appearing with nearly equal frequency. According to the research team, reversing the direction of the internal convection did not alter these probabilities, indicating that the final polarity is dictated by initial weak perturbations. This discovery highlights that the dipole field is not a byproduct of specific convection movements but rather a result of early, minute fluctuations. The study tracked the magnetic growth through two distinct phases, starting with a period of frequent reversals on a magnetic-diffusion timesc...