The earthquake in Japan has given scientists a wealth of factual material that portends hard times residents of the region the Pacific Ring of Fire. Behavior of faults in the crust remains unpredictable, Tokyo residents may face new powerful earthquake.
The recent earthquake in Japan has again shown the weakness of science in the field of short-term prediction of seismic events. A particular difficulty was the fact that the most powerful quake occurred on the ocean floor, and sophisticated monitoring equipment installed on the ground, almost does not allow any conclusions about the offshore seismic activity.
Science magazine published just three studies in which the reasons of the unexpected power of Japanese earthquake.
In addition, scientists point to the danger of a new powerful earthquake just south of the — in the capital, Tokyo.
Earthquake occurred demonstrated the limitations of modern seismology. "We did not know what is happening south of the epicenter of the earthquake on March 11," — the author of one of the works by Mark Simons of the University of California in Pasadena.
Before the earthquake, many experts agree that the offshore fault north of Tokyo is not hidden anything unpredictable. In this part of the oceanic lithospheric plate crawls under mainland, which is Japan (the so-called subduction zone). These areas are traditionally characterized by a large number of earthquakes and volcanic eruptions. With the subsidence of the oceanic crust in the mantle of accumulated stress, which leads to the tremors.
However, scientists do not expect a massive earthquake, but several minor seismic events that could not cause serious damage.
This opinion was based on the fault of a few centuries of observations in the area of the earthquake of magnitude 8.7 occurred every few decades.
However, the fault has shown a different pattern of behavior: March 11, 2011 was a giant in strength earthquake of magnitude 9. Now research efforts aimed at to assess the size of the Earth's crust displacement fracture as a result of the push. For this purpose were collected and analyzed seismic data from around the world using satellite observations, where crustal movements in Japan, and also collected data on the tsunami received stations on buoys in the ocean.
Group Satoci Ide of the University of Tokyo compared the main earthquake seismic markers with parameters of its predecessor, the strongest a magnitude of 7.3, and a group of Mariko Sato, operating in coastal protection, measured the movement of the sea floor. "It's hard to imagine a more qualitatively documented earthquake" — agrees David Ould from the National Geological Service of the United States.
Joint assessment scientists
offset plates in the subduction zone of the earthquake was 50-60 meters.
This is a huge figure is 2-3 times higher than the previous documented shift in the earthquake in Chile, a magnitude 8.8. No less striking is the structure of the event. In the motion came just five adjacent segments of the fault, covering the territory of almost 600 km. Scientists suggest the simultaneous movement of only one or two sites. Hardest moved two central plot.
All this suggests that the difference — much more complex structure than previously anticipated. What remains unclear is another important question is whether an earthquake to diluted accumulated stress, or some part of the fault remains tense? If the latter is true, the people of Tokyo should prepare for a new serious earthquake. For example, an earthquake in the Indian Ocean in 2004 a magnitude 9.3, the subsequent tsunami that killed 300,000 people, followed by re-powerful thrust of magnitude 8.7, occurred in just 3 months.