Japan: New Work Reinforces Megaquake's Harsh Lessons in Geoscience(sibling quake near Tokyo?)

Science Magazine ^ | 05/20/11 | Richard A. Kerr

[TigerLikesRooster]

New Work Reinforces Megaquake's Harsh Lessons in Geoscience

Richard A. Kerr

High-tech analyses of Japan's March earthquake overturn long-held views of fault behavior and warn that another disaster may be looming.

The moment the Tohoku-Oki earthquake struck off northern Japan on 11 March, many researchers knew their expectations had been shattered. The great offshore fault could not be counted on to behave at all predictably. And using onshore observations to gauge whether an offshore fault is building toward failure has grave limitations.

Now three papers (http://scim.ag/MSimons, http://scim.ag/S-Ide, and http://scim.ag/M-Sato) published online this week in Science help show why the inevitable release of seismic energy failed to play out as expected and why monitoring from afar fell short. The papers also point to a possible huge quake to the south, closer to Tokyo. Seismologists are concerned, says Mark Simons of the California Institute of Technology in Pasadena, but they are also now acutely aware of their limitations. “We have no idea what's going on” to the south, he says, but they're anxious to find out.

/snip

If the offshore southern portion is indeed stuck, Simons and colleagues see “the possibility of a sibling to the 2011 event” that could be “similar to what just occurred offshore,” but half as far from Tokyo. So researchers are anxious to find out whether the stress transferred southward from the 9 has accelerated slow slip on the fault and thus defused the threat of a quake. If the fault isn't slipping, another quake would be in the works. Speed is of the essence: A magnitude-8.7 sibling quake followed the 2004 Indian Ocean megaquake by 3 months.

[TigerLikesRooster]

This adds more credence to the fear that long-heralded Tokai Earthquake is coming soon.

[ken5050]

From the first para..the "idea that a fault should behave predictably" smacks of such hubris....

It is no doubt the best documented and studied event ever, yet the more we learn, the more we also realize that we know next to nothing..

Have you see any articles about what they are going to do along the coast, were some towns were completely wiped out. Will they rebuild?..or just relocate everyone inland? Recall that after a tsunami wiped out most of downtown Hilo, Hawaii ..I think it was in the 50's..the entire city center was moved several miles inland..

[TigerLikesRooster]

Media coverage is mostly about those around Fukushima being relocated, and government compensation to those affected by the spread of radioactive substances. I haven't heard much about where to rebuild towns. I am sure they are still debating.

[VanShuyten]

A very dangerous part of the Tokai quake fault is located onshore, running right through the city of Shizuoka. This article is about the Japan Trench quakes north of the Tokai-Japan Trench area. There was a M6 quake near the on-shore Tokai fault just a few weeks after the M9, but the expected major quake along the on-shore portion of the Tokai fault is still overdue. The threat from the off-shore quake, expected to be similar to the M9 in March, was the main reason the Japanese government decided to shut down the Hamaoka nuclear plants in Shizuoka Prefecture.

I lived in Shizuoka-ken for over a decade, and both Mrs. VanShuyten and I are happy to be here in Virginia.

[lefty-lie-spy]

All this says is that earthquakes are STILL unpredictable. When it happens, it happens. So what? I hope I survive, but that’s about it. I rather enjoy the earthquakes anyway.

[Iris7]

The “slipping” of materials under even very linear stress increases is mathematically chaotic. Past behavior is not a predictor in such systems. Even with massive instrumentation, unfortunately.

All you can say, with a high degree of confidence, is that Japan historically has been prone to earthquakes. One can infer that, more than likely, a magnitude 10 earthquake will happen less often than a magnitude 7 earthquake over a “long enough” period of time.

Humans hate and fear uncertainty, of course, and so tell themselves stories to make themselves less fearful and increase social bonding. Such is human nature.