Featured Research

from universities, journals, and other organizations

Strong Earth Tides Can Trigger Earthquakes, UCLA Scientists Report

Date:
October 22, 2004
Source:
University Of California - Los Angeles
Summary:
Earthquakes can be triggered by the Earth's tides, UCLA scientists confirmed Oct. 21 in Science Express, the online journal of Science. Earth tides are produced by the gravitational pull of the moon and the sun on the Earth, causing the ocean's waters to slosh, which in turn raise and lower stress on faults roughly twice a day.

Earthquakes can be triggered by the Earth's tides, UCLA scientists confirmed Oct. 21 in Science Express, the online journal of Science. Earth tides are produced by the gravitational pull of the moon and the sun on the Earth, causing the ocean's waters to slosh, which in turn raise and lower stress on faults roughly twice a day. Scientists have wondered about the effects of Earth tides for more than 100 years. (The research will be published in the print version of Science in November.)

Related Articles


"Large tides have a significant effect in triggering earthquakes," said Elizabeth Cochran, a UCLA graduate student in Earth and space sciences and lead author of the Science paper. "The earthquakes would have happened anyway, but they can be pushed sooner or later by the stress fluctuations of the tides."

"Scientists have long suspected the tides played a role, but no one has been able to prove that for earthquakes worldwide until now," said John Vidale, UCLA professor of Earth and space sciences, interim director of UCLA's Institute of Geophysics and Planetary Physics, and co-author of the paper. "Earthquakes have shown such clear correlations in only a few special settings, such as just below the sea-floor or near volcanoes."

"There are many mysteries about how earthquakes occur, and this clears up one of them," Vidale said. "We find that it takes about the force arising from changing the sea level by a couple of meters of water to noticeably affect the rate of earthquakes. This is a concrete step in understanding what it takes to set off an earthquake."

Cochran, Vidale and co-author Sachiko Tanaka are the first researchers to factor in both the phase of the tides and the size of the tides, and are using calculations of the effects of the tides more accurate than were available just three years ago. Tanaka is a seismologist with Japan's National Research Institute for Earth Science and Disaster Prevention.

Cochran and Vidale analyzed more than 2,000 earthquakes worldwide, magnitude 5.5 and higher, which struck from 1977 to 2000. They studied earthquakes in "subduction zones" where one tectonic plate dives under another, such as near the coasts of Alaska, Japan, New Zealand and western South America. "These earthquakes show a correlation with tides because along continent edges ocean tides are strong," Vidale said, "and the orientation of the fault plane is better known than for faults elsewhere."

Cochran conducted a statistical analysis of the earthquakes and tidal stress data, using state-of-the-science tide calculations from Tanaka and the best global earthquake data, which came from Harvard seismologists. This research follows up on a 2002 study by Tanaka. The current research was funded by the National Science Foundation and the Laurence Livermore National Laboratory.

Cochran and Vidale found a strong correlation between when earthquakes strike and when tidal stress on fault planes is high, and the likelihood of these results occurring by chance is less than one in 10,000, Cochran said. They found that strong tides impose enough stress on shallow faults to trigger earthquakes. If the tides are very large, more than two meters, three?quarters of the earthquakes occur when tidal stress acts to encourage triggering, she found. Fewer earthquakes are triggered when the tides are smaller.

In California, and in fact in most places in the world, the correlation between earthquakes and tides is considerably smaller, Vidale said. In California, tides may vary the rate of earthquakes at most one or two percent; the overall effect of the tides is smaller, he said, because the faults studied are many miles inland from the coast and the tides are not particularly large.


Story Source:

The above story is based on materials provided by University Of California - Los Angeles. Note: Materials may be edited for content and length.


Cite This Page:

University Of California - Los Angeles. "Strong Earth Tides Can Trigger Earthquakes, UCLA Scientists Report." ScienceDaily. ScienceDaily, 22 October 2004. <www.sciencedaily.com/releases/2004/10/041022103948.htm>.
University Of California - Los Angeles. (2004, October 22). Strong Earth Tides Can Trigger Earthquakes, UCLA Scientists Report. ScienceDaily. Retrieved November 23, 2014 from www.sciencedaily.com/releases/2004/10/041022103948.htm
University Of California - Los Angeles. "Strong Earth Tides Can Trigger Earthquakes, UCLA Scientists Report." ScienceDaily. www.sciencedaily.com/releases/2004/10/041022103948.htm (accessed November 23, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Sunday, November 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Anglerfish Rarely Seen In Its Habitat Will Haunt You

Anglerfish Rarely Seen In Its Habitat Will Haunt You

Newsy (Nov. 22, 2014) For the first time Monterey Bay Aquarium recorded a video of the elusive, creepy and rarely seen anglerfish. Video provided by Newsy
Powered by NewsLook.com
Raw: Buffalo Residents Digging Out, Helping out

Raw: Buffalo Residents Digging Out, Helping out

AP (Nov. 22, 2014) Hundreds of volunteers joined a 'shovel brigade' in Buffalo, New York on Saturday, as the city was living up to its nickname, "The City of Good Neighbors." Video provided by AP
Powered by NewsLook.com
Toyota's Hydrogen Fuel-Cell Green Car Soon Available in the US

Toyota's Hydrogen Fuel-Cell Green Car Soon Available in the US

AFP (Nov. 21, 2014) Toyota presented its hydrogen fuel-cell compact car called "Mirai" to US consumers at the Los Angeles auto show. The car should go on sale in 2015 for around $60.000. It combines stored hydrogen with oxygen to generate its own power. Duration: 01:18 Video provided by AFP
Powered by NewsLook.com
Google Announces Improvements To Balloon-Borne Wi-Fi Project

Google Announces Improvements To Balloon-Borne Wi-Fi Project

Newsy (Nov. 21, 2014) In a blog post, Google said its balloons have traveled 3 million kilometers since the start of Project Loon. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins