Featured Research

from universities, journals, and other organizations

Izmit earthquake (Turkey): Early warning signals detected for the first time

Date:
February 18, 2011
Source:
CNRS (Délégation Paris Michel-Ange)
Summary:
The 1999 Izmit earthquake in Turkey is one of the best recorded in the world. For the first time, researchers observed that the earthquake was preceded by a preparatory phase that lasted 44 minutes before the rupture of the fault. This phase, which was characterized by a distinctive seismic signal, corresponds to slow slip at depth along the fault. Detecting it in other earthquakes might make it possible to predict some types of earthquakes several tens of minutes before fault rupture.

The 1999 Izmit earthquake in Turkey is one of the best recorded in the world. For the first time, researchers from CNRS, Kandilli Observatory (Istanbul) and the Tubitak research center observed that the earthquake was preceded by a preparatory phase that lasted 44 minutes before the rupture of the fault. This phase, which was characterized by a distinctive seismic signal, corresponds to slow slip at depth along the fault. Detecting it in other earthquakes might make it possible to predict some types of earthquakes several tens of minutes before fault rupture.

These findings are published in the 18 February 2011 issue of the journal Science.

A large earthquake has a magnitude of 7 or more on the Richter scale. In the twentieth century, nine earthquakes of this type occurred along the North Anatolian fault, one of the most active large faults in the world. The 1999 Izmit earthquake had a magnitude of 7.6 and devastated part of northwest Turkey, not far from Istanbul. It was caused by a strike-slip fault that separates the Anatolian plate, which is moving westwards, from the eastward-moving Eurasian plate, and was one of the best-recorded large earthquakes in the world. Since 1999, a team of CNRS researchers, in collaboration with Turkish seismologists, has been studying this earthquake-prone region.

The scientists recently analyzed seismic recordings obtained close to the epicenter of the Izmit earthquake. They detected a highly distinctive seismic signal that had never been previously observed, just before the fault ruptured. More specifically, the recordings revealed a succession of repeated similar vibrations that lasted for a period of 44 minutes. Although this ground motion was almost continuous, it was too faint to be felt by the population. It continued right up until the earthquake, with steadily increasing intensity. Analysis of the signal shows that it was caused by slow, discontinuous slip of the fault in the region where the earthquake occurred. The signal shows that the fault began to slip at depth 44 minutes before rupture occurred. The slip then continued, steadily accelerating, up until the earthquake.

The Izmit earthquake thus began with the slow slip of the fault at the base of the brittle part of Earth's crust, at a depth of around 15 kilometers. The signal detected by the researchers, a clear seismic signature of slow slip, indicates the preparatory phase of the earthquake. Although this was predicted by theory and by laboratory experiments, it had never been demonstrated until now. Measuring instruments at GPS stations located near the fault were not sensitive enough to measure the process directly, which partly explains why the signal went unnoticed at the time. Only a very detailed analysis of the recordings has now made this possible. In addition, the researchers were able to base their work on an exceptionally well-recorded earthquake whose mechanism was more or less ideally suited to detecting a possible preparatory phase. According to the scientists, this phase is likely to exist in other earthquakes, especially of the Izmit type. Both its relatively long duration (44 minutes) and the fact that it emitted a highly distinctive signal are encouraging factors. If new observations support the existence of this preparatory phase in other earthquakes, it might at last become possible to predict some earthquakes tens of minutes before the rupture of the fault.

In France the laboratories involved are: Institut des Sciences de la Terre (CNRS/Universités Grenoble 1 and Chambéry/IRD/LCPC), Institut de Physique du Globe de Strasbourg (CNRS/Université de Strasbourg) and Institut de Physique du Globe de Paris (CNRS/UPMC/Université Paris Diderot), with the support of Agence nationale pour la recherche (ANR).


Story Source:

The above story is based on materials provided by CNRS (Délégation Paris Michel-Ange). Note: Materials may be edited for content and length.


Journal Reference:

  1. M. Bouchon, H. Karabulut, M. Aktar, S. Ozalaybey, J. Schmittbuhl, M.-P. Bouin. Extended Nucleation of the 1999 Mw 7.6 Izmit Earthquake. Science, 2011; 331 (6019): 877 DOI: 10.1126/science.1197341

Cite This Page:

CNRS (Délégation Paris Michel-Ange). "Izmit earthquake (Turkey): Early warning signals detected for the first time." ScienceDaily. ScienceDaily, 18 February 2011. <www.sciencedaily.com/releases/2011/02/110218083606.htm>.
CNRS (Délégation Paris Michel-Ange). (2011, February 18). Izmit earthquake (Turkey): Early warning signals detected for the first time. ScienceDaily. Retrieved July 23, 2014 from www.sciencedaily.com/releases/2011/02/110218083606.htm
CNRS (Délégation Paris Michel-Ange). "Izmit earthquake (Turkey): Early warning signals detected for the first time." ScienceDaily. www.sciencedaily.com/releases/2011/02/110218083606.htm (accessed July 23, 2014).

Share This




More Earth & Climate News

Wednesday, July 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

New Orleans Plans to Recycle Cigarette Butts

New Orleans Plans to Recycle Cigarette Butts

AP (July 21, 2014) — New Orleans is the first U.S. city to participate in a large-scale recycling effort for cigarette butts. The city is rolling out dozens of containers for smokers to use when they discard their butts. (July 21) Video provided by AP
Powered by NewsLook.com
Shark Sightings a Big Catch for Cape Tourism

Shark Sightings a Big Catch for Cape Tourism

AP (July 21, 2014) — A rise in shark sightings along the shores of Chatham, Massachusetts is driving a surge of eager vacationers to the beach town looking to catch a glimpse of a great white. (July 21) Video provided by AP
Powered by NewsLook.com
Spectacular Lightning Storm Hits London

Spectacular Lightning Storm Hits London

AFP (July 19, 2014) — A spectaCular lightning storm struck the UK overnight Friday. Images of lightning strikes over the Shard and Tower Bridge in central London. Duration: 00:23 Video provided by AFP
Powered by NewsLook.com
A Centuries' Old British Tradition Is Far from a Swan Song

A Centuries' Old British Tradition Is Far from a Swan Song

AFP (July 19, 2014) — As if it weren't enough that the Queen is the Sovereign of the UK and 15 other Commonwealth realms, she is also the owner of all Britain's unmarked swans. Duration: 02:18 Video provided by AFP
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