The large gravitational anomaly lasted for about two years over the eastern Atlantic Ocean. It peaked in January 2007, the same month Steve Jobs announced the first iPhone (though, of course, there was no connection between the two events).
The strange anomaly, and the jerk, were caused by a previously unknown geological process, the researchers suspect. Their findings, published Aug. 28 in the journal Geophysical Research Letters, indicated that a shift in minerals may have caused a rapid redistribution of mass in the deep mantle, near the core, altering Earth’s magnetic field.