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Improving earthquake forecasts

ASU research can help communities be better prepared for a possible quake.
March 11, 2016

ASU researchers develop new technique to better understand where temblors are more likely to occur, help communities prepare

Some of the world's largest earthquakes occur on subduction zones, where a cold dense oceanic plate moves under a warmer continental plate. This was the case for the massive Tohoku earthquake in Japan in 2011, which was followed by a tsunami with waves up to 33 feet that left thousands dead and inflicted extensive damage to buildings and infrastructure, including four major nuclear power stations. 

Manoochehr Shirzaei, an assistant professor at ASU’s School of Earth and Space Exploration, and Jennifer Weston, a former postdoctoral researcher at the school, have published a new technique for observing the behavior of these destructive tectonic settings and forecasting earthquakes in the journal Tectonophysics. (Weston is now at the International Seismological Centre in England.)

Shirzaei and Weston used measurements of surface displacement with GPS, in combination with the location and magnitude of characteristically repeating earthquakes, to investigate how the Japan subduction zone was behaving prior to a large earthquake.

A satellite view of Japan and the ocean.

Some of the world's largest earthquakes
occur on subduction zones, where a cold
dense oceanic plate moves under a
warmer continental plate. Japan and the
ocean to its east are pictured here.

Photo by Visible Earth/NASA

“We were trying to see if GPS and data on characteristically repeating earthquakes could be successfully combined to investigate the movement (creep) or lack of movement (locking) on the plate interface,” said Weston.

In their study, Weston and Shirzaei compared the location of areas of the subduction zone that were moving “fast” (8 cm/year) and “slow” (0-2 cm/year) with the location of certain properties of the subduction zone.

They began to see a link between the two that could help them understand why some parts of the subduction zone move relatively quickly but not very often, and why other parts move often but slowly (creep) in the period between large earthquakes. 

Having an estimate of areas that are not creeping is useful for understanding where earthquakes are more likely to occur in the future.  

A conceptual model of the creep mechanism in northeast Japan

A conceptual model of the creep mechanism in northeast Japan. As the cooler oceanic lithosphere subducts it becomes dehydrated, releasing fluid that migrates along the fractures in the plate. The fluid becomes trapped due to reduced porosity and permeability, and the clay acts as a weakening mechanism, thus facilitating creep. This part of the plate can also move in a stick-slip manner if the lubricating pore-fluid pressure drops. The upper part of the plate, where the pore-fluid pressure is lower, ruptures in large earthquakes.

"The Tohoku earthquake surprised the seismological community and challenged the conventional ideas about subduction zones behavior,” said Shirzaei. “This research provides unique data sets that update our understanding of these zones, and aid in the revision of earthquake forecast models, with the aim of avoiding future surprises."

The research is unique in that it combined GPS and repeating earthquake data to look at subduction zones and used seismic tomography to solve for its mechanical properties. While these are different data sets, they are complementary. In addition, the researchers used a data set spanning most of the northeast Japan coast and over a period of nearly eight years.

“This information can be used to help communities be better prepared for a possible event,” said Weston. “And considering millions of people live adjacent to subduction zones, this is valuable information.”

The School of Earth and Space Exploration is an academic unit of ASU's College of Liberal Arts and Sciences.

Top photo: An upended house is among debris in Ofunato, Japan, after a 9.0-magnitude earthquake and subsequent tsunami in March 2011. Photo by Matthew M. Bradley/U.S. Navy

Karin Valentine

Media Relations & Marketing manager, School of Earth and Space Exploration

480-965-9345

 
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ASU setting path 'Toward a More Perfect University'

Ivy League author praises innovations, widened access at ASU.
'Ivy League is not where it's at,' author says, praising ASU's initiatives.
March 11, 2016

Ivy League author praises innovations launched by ASU President Crow

An Ivy League academic made a startling prediction at a talk at Arizona State University on Friday: Knowledge is progressing so quickly that the concept of a standalone university could soon be obsolete.

Jonathan Cole (pictured above), former provost at Columbia University, made that forecast during a discussion of his new book, “Toward a More Perfect University,” with ASU President Michael Crow in the Memorial Union on the Tempe campus.

“Instead of creating more sports leagues, what we should do is produce academic leagues,” said Cole, who is the John Mitchell Mason Professor of the University at ColumbiaCole also is the former dean of faculties and vice president for arts and sciences at Columbia.. “Why not form a league that’s not based upon a school or a department, but based upon a problem?”

In Cole’s example, complex issues such as the study of inequality of wealth would be studied by a collaboration of the top minds around the world, enabled by technology.

“We’re so far from our maximum in terms of universities’ potential that we should rethink every aspect of them,” he said.

ASU President Michael Crow

ASU President Michael Crow (right) and Columbia professor and author Jonathan Cole discuss the future of higher education Friday in Tempe. Photos by Charlie Leight/ASU Now

CrowBefore coming to ASU in 2002, Crow was executive vice provost of Columbia, where he also was professor of science and technology policy in the School of International and Public Affairs. said that universities need to challenge the “hierarchy of knowledge,” which has become distorted.

“We’ve built this social hierarchy that physics is the elite science and everything else is trivial by comparison. Why do we have ‘physics is better than chemistry,’ ‘chemistry is better than biology’? ‘Economics is more important than political science, which is more important than sociology’?

“The understanding of each is equal.”

Cole said that Crow has been a driver of innovation at ASU to a degree almost unheard of in higher education.

“Most leaders of academic institutions are risk averse, not risk takers,” Cole said. “Michael Crow is a prudent risk taker.”

Toward a More Perfect University bookIn his book, Cole refers to ASU as “a cauldron of change,” citing Crow’s creation of transdisciplinary research initiatives such as the Biodesign Institute, as well as programs such as the Global Freshman Academy and the Starbucks Initiative.

“Every time I come to ASU, I see amazing things unfold in front of my eyes. It’s a level of excellence that you rarely see in an American university combined with access and really giving people opportunities,” Cole said.

Cole said that admission to Ivy League colleges has become so impossibly selective that the students are “boring.”

“They all have perfect scores. They’ve never deviated from the beaten path. They’ve never flunked chemistry,” he said.

“They have taken the quirkiness out of the student body.”

He praised ASU for taking students from a wide variety of backgrounds.

“ASU doesn’t pay homage to the kind of testing mythology that has been internalized in American society as legitimate.”

He said that although his entire education and career have been spent at Columbia, “The Ivy League is not where it’s at.

“Most education and most research is taking place at state universities, and we cannot let them fail.”

Mary Beth Faller

reporter , ASU Now

480-727-4503