Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Chile quake occurred in zone of “increased stress”

02.03.2010
The massive, 8.8-magnitude earthquake that struck Chile Feb. 27 occurred in an offshore zone that was under increased stress caused by a 1960 quake of magnitude 9.5, according to geologist Jian Lin of the Woods Hole Oceanographic Institution (WHOI).

The earthquake, some 300-500 times more powerful than the magnitude 7.0 quake in Haiti Jan. 12, ruptured at the boundary between the Nazca and South American tectonic plates.

The temblor was triggered when the “subducting” Nazca plate was thrust under the South American plate, uplifting a large patch of the seafloor and prompting tsunami warnings throughout the Pacific Ocean. The two plates are converging at a rate of 80 mm per year, says Lin, “which is one of the fastest rates on Earth.”

Lin and colleague Ross S. Stein of the U.S. Geological Survey in Menlo Park, Ca., have studied the region extensively, and alerted the scientific community to a build up of stress along the interface of the two plates in a 2004 paper in the Journal of Geophysical Research.

“In 2004, we calculated that the 1960 magnitude 9.5 earthquake has caused large stress increase on both the northern and southern ends of its rupture,” said Lin. That quake, centered a few hundred kilometers south of Saturday’s earthquake, was the largest instrumentally recorded earthquake in the world. It killed 1,655 people in southern Chile and unleashed a tsunami that crossed the Pacific, killing 61 people in Hawaii and 185 in Japan. Saturday’s “quake picked up where the 1960 rupture ended in the north,” Lin said.

“This story is quite similar to the Dec. 26, 2004 magnitude-9.0 Sumatra earthquake, which was followed by a magnitude 8.7 quake on its southern end on 28 March 2005,” he said. “The only difference is that it took 50 years for the northern neighboring section of the 1960 [Chile] earthquake to rupture, while it took only 3 months for the southern adjacent segment to rupture in Sumatra.

“We do not yet have good enough science to say why one place took only 3 months and another took 50 years. But even 50 years is short enough [to fall within] in a person's lifetime. Thus, we should consider the earthquake interaction possibilities seriously.”

In Haiti, Lin pointed out that he and others have calculated that the Jan. 12 rupture has heightened stress further east along the Enriquillo Fault, thereby increasing chances of a quake in that region, which “comes within five kilometers of Port-au-Prince,” he said.

The latest Chile quake, which had killed more than 700 people as of March 1, was centered some 65 miles west-southwest of Talca, Chile, about 21.7 miles below the ocean’s surface, “relatively shallow for a subduction quake,” said Lin. It struck about 200 miles southwest of Santiago, the country’s capitol. Saturday’s earthquake had a “much longer” rupture zone—500-600 km—than that of the Haiti quake—35-50 km, Lin said.

“So why was the Haiti quake so much more catastrophic than the Chile quake?” he asked.

“First, as a nation, Chile is much better prepared for earthquakes than Haiti. People in Chile today still remember the pain of the 1960 quake,” Lin said. In addition, coastal Chile has a history of other very large earthquakes. Since 1973, there have been 13 events of magnitude 7.0 or greater. Approximately 870 km to the north of the Feb. 27 earthquake is the source region of the magnitude 8.5 earthquake of November 1922. That great quake significantly killed several hundred people and caused severe property damage. The 1922 quake generated a 9-meter local tsunami that inundated the Chile coast near the town of Coquimbo; the tsunami also crossed the Pacific, washing away boats in Hilo harbor, Hawaii.

“In contrast, the last catastrophic earthquake in Haiti was 240 years ago,” Lin said, “and thus few people were aware of a string of ‘earthquake bombs’ lying next to Port-au-Prince until Jan. 12.

“Second,” he said, “the economy of Chile is much better than that of Haiti. Thus, building codes are better developed and enforced in Chile. The contrasts between the aftermaths of the Chile and Haiti quakes reminded us, once again, that ‘earthquakes do not kill people, buildings do.’”

The Chile temblor dispatched tsunami waves onshore to Chile and across the Pacific Ocean toward Hawaii and the west coast of the US mainland, primarily California, and experts warned that tsunami waves were likely to hit Asian, Australian and New Zealand shores within 24 hours of the earthquake. Waves 6 feet (1.8 meters) above normal hit Talcahuano near Concepcion 23 minutes after the quake, and President Michelle Bachelet said a huge wave swept into a populated area in the Robinson Crusoe Islands, 410 miles (660 kilometers) off the Chilean coast. There were no immediate reports of major damage from the waves.

Though the predicted tsunami waves did reach Hawaii, California, New Zealand and other Pacific Rim regions, they proved to be relatively small and had minimal impact. “Even though the waves turned out to be not devastating”, Lin said, “it was an important opportunity for communities in coastal regions to improve the preparedness for potential greater tsunamis in the future.”

The WHOI research vessel Atlantis was operating off the coast of northern Chile when the magnitude 8.8 earthquake struck on Saturday. WHOI confirmed that R/V Atlantis and all on board are safe. There were no ill effects to R/V Atlantis or those on board from the quake or the subsequent tsunami.

R/V Atlantis has a scheduled port stop beginning on March 3, 2010, in Arica, Chile, which is on the northern coast of Chile. The WHOI Marine Operations Department is assessing the situation with their port agents to determine how or if that port stop will be affected.

A number of WHOI staff are onboard the R/V Melville, operated by Scripps Institution of Oceanography, which is conducting research at the Chile Triple Junction. WHOI received an email from an employee aboard the ship, and was told that all onboard are fine. The blog associated with this expedition (http://oceanexplorer.noaa.gov/explorations/10chile/) had not been updated on Saturday because, WHOI was told, the ship’s communication capability was being used to communicate by those onboard with family on shore.

The Woods Hole Oceanographic Institution is a private, independent organization in Falmouth, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans' role in the changing global environment.

Media Relations | EurekAlert!
Further information:
http://www.whoi.edu
http://oceanexplorer.noaa.gov/explorations/10chile/

More articles from Earth Sciences:

nachricht Glacial engineering could limit sea-level rise, if we get our emissions under control
20.09.2018 | European Geosciences Union

nachricht Warning against hubris in CO2 removal
20.09.2018 | Mercator Research Institute on Global Commons and Climate Change (MCC) gGmbH

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Scientists present new observations to understand the phase transition in quantum chromodynamics

The building blocks of matter in our universe were formed in the first 10 microseconds of its existence, according to the currently accepted scientific picture. After the Big Bang about 13.7 billion years ago, matter consisted mainly of quarks and gluons, two types of elementary particles whose interactions are governed by quantum chromodynamics (QCD), the theory of strong interaction. In the early universe, these particles moved (nearly) freely in a quark-gluon plasma.

This is a joint press release of University Muenster and Heidelberg as well as the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt.

Then, in a phase transition, they combined and formed hadrons, among them the building blocks of atomic nuclei, protons and neutrons. In the current issue of...

Im Focus: Patented nanostructure for solar cells: Rough optics, smooth surface

Thin-film solar cells made of crystalline silicon are inexpensive and achieve efficiencies of a good 14 percent. However, they could do even better if their shiny surfaces reflected less light. A team led by Prof. Christiane Becker from the Helmholtz-Zentrum Berlin (HZB) has now patented a sophisticated new solution to this problem.

"It is not enough simply to bring more light into the cell," says Christiane Becker. Such surface structures can even ultimately reduce the efficiency by...

Im Focus: New soft coral species discovered in Panama

A study in the journal Bulletin of Marine Science describes a new, blood-red species of octocoral found in Panama. The species in the genus Thesea was discovered in the threatened low-light reef environment on Hannibal Bank, 60 kilometers off mainland Pacific Panama, by researchers at the Smithsonian Tropical Research Institute in Panama (STRI) and the Centro de Investigación en Ciencias del Mar y Limnología (CIMAR) at the University of Costa Rica.

Scientists established the new species, Thesea dalioi, by comparing its physical traits, such as branch thickness and the bright red colony color, with the...

Im Focus: New devices based on rust could reduce excess heat in computers

Physicists explore long-distance information transmission in antiferromagnetic iron oxide

Scientists have succeeded in observing the first long-distance transfer of information in a magnetic group of materials known as antiferromagnets.

Im Focus: Finding Nemo's genes

An international team of researchers has mapped Nemo's genome

An international team of researchers has mapped Nemo's genome, providing the research community with an invaluable resource to decode the response of fish to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

One of the world’s most prominent strategic forums for global health held in Berlin in October 2018

03.09.2018 | Event News

4th Intelligent Materials - European Symposium on Intelligent Materials

27.08.2018 | Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

 
Latest News

Glacial engineering could limit sea-level rise, if we get our emissions under control

20.09.2018 | Earth Sciences

Warning against hubris in CO2 removal

20.09.2018 | Earth Sciences

Halfway mark for NOEMA, the super-telescope under construction

20.09.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>