Japan 9.0 Tohoku-Oki earthquake and surprising findings

Japan 9.0 Tohoku -Oki Earthquake Surprising findings about energy distribution over fault slip and stress accumulation- nuclear energy

When the magnitude 9.0 Tohoku-Oki earth quake and resulting tsunami struck off north east coast of Japan on March 11, they caused wide spread destruction and death. Using observations from dense regional geodetic net work ( allowing measurements of earth movements to be gathered from GPS satellite data) globally distributed broad bank seismographic net work, and open ocean tsunamic  data, researchers have begun to construct numerous models that describe how earth moved that day.

Now a study led by researchers at California institute of technology ( Caltech) published on line in May 19 issue of science express, explains the first large set of observational data from this rare mega thrust event.

“ this  event is best recorded great earthquake over “ says Mark Simon professor of geophysics at Caltech’s seismological laboratory and lead author of study. For scientists  working  to improve infrastructure and prevent loss of life through better application of seismological data, observations from event will help inform future research priorities.

Simons  says one of most interesting findings of data analysis was spatial compactness of the event. The mega thrust  earth quake occurred at subduction  zone where pacific plates dips below Japan. The length of fault that experienced significant slip during the Tohoku earthquake was about 250 kilometers about half what would be conventionally expected for an event of this magnitude.

Future more, the area where fault slipped the most- 30 meters or more -happened within 50-60 kilometer long segment. “ This is not some thing we have documented before “ says Simons.

“I am sure it has happened in the past, but technology has advanced only past 10 to 15 years to the point where we can measure these slips much more accelerately  through GPS and other data.”

For Jean Paul Ampuero assistant professor of seismology at Caltech’s seismological laboratory who studies earthquake dynamics, the most significant finding was that high-and low frequency seismic waves can come different areas of fault. “The high frequency seismic waves in the Tohoku earth quake were generated much closer to coast away from area of the slip where we saw low frequency waves. “ he says. Simons says there are two factors controlling behavior : one is because the larger amount of stress ( which is what generates high frequency waves ) was found at edges of slip not near centre of where fault began to break. He compares to finding to what happens when rip of piece of paper in half. “ The highest  amount of stress are not found where paper has not been torn” he explains. “ We  had previously thought high frequency energy was an indicator of fault slippage , but it did not correlate in our models of this event . “

Equally important is how the fault reacts to these stress concentrations it appears that only deeper, segments of fault respond to these stresses by producing high frequency energy.

Ampuero says the implications of these observation of mechanical properties of tectonic faults need to be further explored and integrated in physical models of earthquake,  which will help scientists better quantify earthquake hazards.

“ We learn from each significant earth quake, especially if earthquake is large and recorded by sensors” says Ampuero. “The Tohoku earthquake was recorded by up words of 10 times more sensors at near fault distances than any other earthquake. This provide a sharper and robust view of earthquake rupture processes and their effects.”

For seismologist Hiro  Kanamori Cal techs professor of Geo-physics, Emeritus who was in Japan at the time of earthquake and has been studying the region many years, the most significant finding was that large slip occurred near Japan trench. While smaller earthquakes have happened in the area, it was believed that relatively soft material of sea floor would not support large amount of stress. “ The amount of strain associated with large displacement is nearly 5 to 10 times larger than we normally see in large mega thrust earth quakes “ he notes. “It has been generally thought that rocks near Japan trench could not accommodate such large elastic strain.”

The researchers are still unsure why such a large strain was able to accumulate in this a  area. One possibility is that either the sub ducting sea floor or upper plate or (both)have some unusual such as regions that were formerly under water mountain ranges on the pacific plate-that have now been consumed by subduction zone and cause the plates to get stuck and build up stress.

“ Because of this local strengthening - what ever its cause- the pacific plate and Okhotsk plate had been pinned together for long time, probably 500 to 1000 years and finally failed this magnitude 9.0 event. Says Kanamori. “ Hopefully , detailed geophysical studies of sea floor structure will eventually clarify the mechanism of local strengthening in this area. “

Somans says researchers knew very little about area where earthquake occurred because of limited historical data.

Instead of saying large earth quake probably would not happen there, we should have said that we did not know” he says. Similarly he says the area just south of where fault slipped is similar position, researchers don’t  yet know what might do in the future.

“It is important to note that we are not in predicting an earthquake here “ emphasizes Simons  . “ However we don’t have data on the area, and therefore should focus attention there, given its proximity to Tokyo.”

He says that the relatively new Japan’s seafloor observation systems will prove very useful in scientists attempt to learn more about area.

“Our  study is first foray into what is an enormous quantity of available data “ says Simon s. “ there will be lot more information coming out this event, all which will help us to learn more in order to help inform infrastructure  and safety procedures.”

The work was funded by the Gordon and Betty Moose Foundation, national science foundation grants; the southern California earthquake centre and NASA international research and technology development program.

Effect of massive earthquake on nuclear energy

The observation data from this rare mega thrust earth quake which was lot of bearing on nuclear plants situated Fukushima Daiichi in Japan. The event that occurred is best recorded great earthquake over . Present observations will help avoiding loss of life and destruction and nuclear radiation leakage through better application with seismic data available and also for future conclusion in designing new nuclear reactors.

The technology has developed and advanced last 15 years though we now to  take care such mega thrust earth quake which can prevent  mass damage and develop latest safety technology available to take care precautions to nuclear reactors in event of disaster   . Researchers knew very little about area where earthquake occurred because of limited historical data. Now data is available for scientists and nuclear engineers to develop safety techniques for nuclear reactors in the event of core melting. 

Hence nuclear scientists and engineers to develop and design latest 111 stage nuclear reactors that can with standard massive earthquakes instead of finding faults on nuclear energy which is a safe and clean source energy. Such type of earthquake normally may occur  rare or once thousand years or so. Because of  such disaster we cannot run away and post phone our nuclear program since which  is  safely proved tested technologically developed  energy .      .