In DepthGeophysics

Sloshing of Earth's core may spike big quakes

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Science  03 Nov 2017:
Vol. 358, Issue 6363, pp. 575
DOI: 10.1126/science.358.6363.575

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For decades, scientists have charted tiny fluctuations in the length of Earth's day: Gain a millisecond here, lose a millisecond there. Last week at the annual meeting of the Geological Society of America in Seattle, Washington, two geophysicists argued that these minute changes could be correlated with the timing of major earthquakes—and potentially help forecast them. During the past 100 years, Earth's slowdowns have matched surprisingly well with periods of global increases in the frequency of magnitude-7 and larger earthquakes. Each spike happens well after the slowdown, offering a 5-year heads up on future quakes. So far, researchers have only fuzzy ideas about how changes in Earth's molten iron core might cause this pattern, but they say the finding is too provocative to ignore.