Frequency of Undersea Earthquakes Tied to Ocean Tides

Frequency of Undersea Earthquakes Tied to Ocean Tides

Cheryl Dybas

Scientists studying an active seafloor volcano in the Pacific Ocean have determined that there is a correlation between hundreds of micro-earthquakes and ocean tides.

In research funded by NSF, geophysicist Maya Tolstoy of the Lamont-Doherty Earth Observatory at Columbia University found that earthquakes coming from the Axial Volcano on the Juan de Fuca Ridge (located off the coasts of Washington and Oregon) are occurring during tidal flows when the weight of the water is at a minimum.

Tolstoy and colleagues also found a tidal correlation with signals for harmonic tremors, which researchers believe result from super-heated water moving in cracks in Earth’s crust. The results suggest that seafloor crust is essentially breathing with the ebb and flow of ocean tides, allowing more movement of water through the crust and the release of seismic energy on a regular tidal schedule.

“Scientists have long postulated that earthquakes and tidal movements are somehow connected,” said Tolstoy, “but the link has been difficult to identify. It’s only within the last decade that the technology has been available to make the long-term seismic recordings of the seafloor necessary to finding this correlation. We now have an interesting and important view into how Axial Volcano’s deformation, and perhaps the deformation of other undersea volcanoes, actually works.”