Columbia University study ties the frequency of earthquakes to ocean tides

May 29, 2002

A Columbia University scientist studying an active seafloor volcano in the Pacific Ocean has determined that there is a correlation between the hundreds of micro earthquakes she recorded and the ocean tides.

Dr. Maya Tolstoy, Associate Research Scientist at the Lamont-Doherty Earth Observatory at Columbia University, is publishing in the June issue of the journal Geology, research showing that earthquakes coming from the Axial Volcano on the Juan de Fuca Ridge, located off the coast of Washington and Oregon, are occurring during tidal lows when the weight of the water is at a minimum. Tolstoy and her colleagues also found a tidal correlation with signals for harmonic tremors, which are thought to result from super heated water moving in the cracks.

The research suggests that the seafloor crust is essentially breathing with the 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, but on land the link has been quite difficult to identify. It makes sense that if this correlation were to be seen strongly anywhere, the ocean floor would be the most likely site, since it will be strongly influenced by the tides. However, 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 find this correlation. Our first study on the Axial Volcano began in 1994. Today, we have an interesting and important view into how its deformation, and perhaps the deformation of other underwater volcanoes, works," said Tolstoy.

The Axial Volcano was chosen as a research site because it was thought to be volcanically active. In 1994, Tolstoy and her team deployed equipment on the ocean floor to record both seismic activity and tides. Over a period of two months, 402 micro earthquakes were recorded and they showed both a fortnightly and a diurnal pattern. It was also recorded that there was a two hour lag between the movement of the tides and the deformation of the Earth's crust, which is a process called an Earth tide. This indicates that the movement of water appears to be a more important force in day-to-day earthquake triggering than the movement of the earth.

In 1998, a major eruption on Axial Volcano occurred. The activity observed in 1994 occurred largely at the site of the 1998 eruption and may have indicated precursory volcanic activity at a site on the brink of an eruption. The existence and timing of the earthquakes is also important in understanding the nutrient supply to the biological communities living in these extreme environments devoid of sunlight.

At the time of the experiment, this research constituted the longest period of continuous recording of seismic activity in a single location. Since then, other longer-term deployments have been made, and similar correlations have been observed in additional locations on the Juan de Fuca Ridge. It is therefore probable that ocean tidal influences are occurring elsewhere on the seafloor and on other mid-ocean ridge chains.
-end-
This research was funded with a grant from the National Science Foundation.

Tolstoy is currently conducting analysis of seismic data from the Mid-Atlantic Ridge to look for similar tidal influences on the seafloor of the Atlantic Ocean.

Dr. Tolstoy is a geophysicist at the Lamont-Doherty Earth Observatory, a research unit for the Columbia Earth Institute. She specializes in the design, execution, and analysis of marine seismic experiments. In addition to the Juan de Fuca Ridge, she has ongoing research at the Gakkel Ridge, the South East Indian Ridge, the Australian Antarctic Discordance, the East Pacific Rise, and the Mid-Atlantic Ridge.

The Lamont-Doherty Earth Observatory is one of the world's leading research centers examining the planet from its core to its atmosphere, across every continent and every ocean. From global climate change to earthquakes, volcanoes, environmental hazards and beyond, Observatory scientists continue to provide the basic knowledge of Earth systems that must inform the difficult decisions that will determine the future health and habitability of our planet. For more information, visit www.earth.columbia.edu.

Tolstoy's paper, "The Breathing of the Seafloor: Tidal correlations of Seismicity at Axial Volcano," is published in the June issue of Geology, the scientific journal of the Geological Society of America. To read the abstract of this article, go to: www.gsajurnals.org. To obtain a copy of the article, contact Ann Cairns at acairns@geosociety.org.

Geological Society of America

Related Earthquakes Articles from Brightsurf:

AI detects hidden earthquakes
Tiny movements in Earth's outermost layer may provide a Rosetta Stone for deciphering the physics and warning signs of big quakes.

Undersea earthquakes shake up climate science
Sound generated by seismic events on the seabed can be used to determine the temperature of Earth's warming oceans.

New discovery could highlight areas where earthquakes are less likely to occur
Scientists from Cardiff University have discovered specific conditions that occur along the ocean floor where two tectonic plates are more likely to slowly creep past one another as opposed to drastically slipping and creating catastrophic earthquakes.

Does accelerated subduction precede great earthquakes?
A strange reversal of ground motion preceded two of the largest earthquakes in history.

Scientists get first look at cause of 'slow motion' earthquakes
An international team of scientists has for the first time identified the conditions deep below the Earth's surface that lead to the triggering of so-called 'slow motion' earthquakes.

Separations between earthquakes reveal clear patterns
So far, few studies have explored how the similarity between inter-earthquake times and distances is related to their separation from initial events.

How earthquakes deform gravity
Researchers at the German Research Centre for Geosciences GFZ in Potsdam have developed an algorithm that for the first time can describe a gravitational signal caused by earthquakes with high accuracy.

Bridge protection in catastrophic earthquakes
Bridges are the most vulnerable parts of a transport network when earthquakes occur, obstructing emergency response, search and rescue missions and aid delivery, increasing potential fatalities.

Earthquakes, chickens, and bugs, oh my!
Computer scientists at the University of California, Riverside have developed two algorithms that will improve earthquake monitoring and help farmers protect their crops from dangerous insects, or monitor the health of chickens and other animals.

Can a UNICORN outrun earthquakes?
A University of Tokyo Team transformed its UNICORN computing code into an AI-like algorithm to more quickly simulate tectonic plate deformation due to a phenomenon called a ''fault slip,'' a sudden shift that occurs at the plate boundary.

Read More: Earthquakes News and Earthquakes Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.