Featured Research

from universities, journals, and other organizations

UC Riverside Geophysicist Comments On How Deep Earthquakes Get Started

Date:
September 2, 2003
Source:
University Of California - Riverside
Summary:
In a commentary in the Aug. 21 issue of Nature, Harry Green, Distinguished Professor of Geology and Geophysics in the Institute of Geophysics and Planetary Physics and the department of earth sciences at UC Riverside, explains that two large, deep earthquakes (depth > 300 km below the surface of the earth) that occurred in Aug. 2002 in the Tonga subduction zone were causally related.

RIVERSIDE, Calif. -- In a commentary in the Aug. 21 issue of Nature, Harry Green, Distinguished Professor of Geology and Geophysics in the Institute of Geophysics and Planetary Physics and the department of earth sciences at UC Riverside, explains that two large, deep earthquakes (depth > 300 km below the surface of the earth) that occurred in Aug. 2002 in the Tonga subduction zone were causally related.

The Tonga subduction zone is approximately beneath the Fiji Islands in the Pacific Ocean. The two earthquakes were 300 km apart from each other and the difference in their depth was 65 km. Their magnitudes were 7.6 and 7.7.

In the commentary, Green sheds light on a paper by Tibi et al. also appearing in the Aug. 21 issue of Nature. Tibi et al. argue that the second large earthquake was triggered by the passage of seismic waves generated by the first earthquake.

"Tibi and colleagues' observations are a major advance in understanding deep earthquakes," Green said. "They might provide a new constraint on the mechanism by which these earthquakes begin. Their work provides a major piece of information as to how earthquakes get started, which may in the long run contribute to the prediction of damaging earthquakes that threaten people in California and elsewhere."

The authors demonstrated for the first time remote triggering of one deep earthquake by another. "The Tonga earthquakes occurred only 7 minutes apart," said Green. "Equally interesting, the triggered earthquake occurred in a place where no earthquakes have ever been recorded before."

Green explained that the observations by Tibi et al. have significant implications for the physical process that initiates deep earthquakes. In the commentary, he outlines the three principal physical mechanisms that have been proposed by geophysicists to explain the initiation of deep earthquakes. "One of these observations can be ruled out by Tibi et al.'s observations," said Green. "Moreover, we can use the recent seismological work of other researchers to show that one of the remaining two mechanisms is the most probable cause." That mechanism is 'phase-transformation-induced faulting,' which Green and a graduate student discovered in 1989.


Story Source:

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


Cite This Page:

University Of California - Riverside. "UC Riverside Geophysicist Comments On How Deep Earthquakes Get Started." ScienceDaily. ScienceDaily, 2 September 2003. <www.sciencedaily.com/releases/2003/09/030902074428.htm>.
University Of California - Riverside. (2003, September 2). UC Riverside Geophysicist Comments On How Deep Earthquakes Get Started. ScienceDaily. Retrieved August 2, 2014 from www.sciencedaily.com/releases/2003/09/030902074428.htm
University Of California - Riverside. "UC Riverside Geophysicist Comments On How Deep Earthquakes Get Started." ScienceDaily. www.sciencedaily.com/releases/2003/09/030902074428.htm (accessed August 2, 2014).

Share This




More Earth & Climate News

Saturday, August 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Pyrenees Orphan Bear Cub Gets Brand New Home

Pyrenees Orphan Bear Cub Gets Brand New Home

AFP (Aug. 1, 2014) The discovery of a bear cub in the Pyrenees mountains made headlines in April 2014. Despire several attempts to find the animal's mother, the cub remained alone. Now, the Pyrenees Conservation Foundation has constructed an enclosure. Duration: 00:31 Video provided by AFP
Powered by NewsLook.com
Rare Whale Fossil Pulled from Calif. Backyard

Rare Whale Fossil Pulled from Calif. Backyard

AP (Aug. 1, 2014) A rare whale fossil has been pulled from a Southern California backyard. The 16- to 17-million-year-old baleen whale fossil is one of about 20 baleen whale fossils known to exist. (Aug. 1) Video provided by AP
Powered by NewsLook.com
Greenpeace Ship Arctic Sunrise Free to Leave Russia

Greenpeace Ship Arctic Sunrise Free to Leave Russia

AFP (Aug. 1, 2014) Greenpeace's ship Arctic Sunrise, held in custody by the Russian authorities since September last year, has departed the Russian city of Murmansk en route for its home port of Amsterdam. Duration: 01:04 Video provided by AFP
Powered by NewsLook.com
Visitors Feel Part of the Pack at Wolf Preserve

Visitors Feel Part of the Pack at Wolf Preserve

AP (July 31, 2014) Seacrest Wolf Preserve on the northern Florida panhandle allows more than 10,000 visitors each year to get up close and personal with Arctic and British Columbian Wolves. (July 31) Video provided by AP
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:
from the past week

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