Quake Was One of Largest

The quake turns out to be one ofthe largest ever recorded.  The researchgroup put together an animation which you likely have to go to  www.gfz-potsdam.deto see properly.  The image shown is toosmall so it is necessary to opt for the higher resolution to really see it playout properly.  It is really worth thetrouble and the extent of the aftershocks becomes clear also.  A lot of rock has moved around.

Undoubtedly this will turn out tobe one of the most studied events in history. Not only is it one of the largest ever experienced, it affected anadjacent fully developed modern economy that had prepared for such an event.  Many things had been put in place that wastested to destruction.

Quite simply, anything built tosurvive and even withstand this event will become the engineering standard forall earthquake zone building.

New Findings On The Developments Of The Earthquake Disaster

by Staff Writers

Potsdam, Germany (SPX) Mar 18, 2011

The earthquake disaster on 11 March 2011 was an event of the century not onlyfor Japan.With a magnitude of Mw = 8.9, it was one of the strongest earthquakesever recorded worldwide. Particularly interesting is that here, two daysbefore, a strong foreshock with a magnitude Mw = 7.2 took place almost exactlyat the breaking point of the tsunami-earthquake.

The geophysicist Joachim Saul from the GFZ German Research Centre forGeosciences (Helmholtz Association) created an animation which shows thesequence of quakes since March 9.

The animated image is available at www.gfz-potsdam.deIt shows the earthquake activity inthe region of Honshu, Japan, measured at the GFZ since 8March 2011. After a seismically quiet 8th March, the morning (coordinateduniversal time UTC) of the March 9 began with an earthquake of magnitude 7.2off the Japanese east coast, followed by a series of smaller aftershocks.

The morning of March 11 sees the earthquake disaster that triggered thedevastating tsunami. This earthquake is followed by many almost severeaftershocks, two of which almost reach the magnitude 8. In the following timeperiod the activity slowly subsides, and is dominated by relatively smallmagnitude 5 quakes, though several earthquakes of magnitude 6 are beingregistered on a daily basis.

The activity of aftershocks focuses mainly on the area of the March 11earthquake. Based on the distribution of the aftershocks, the length of thefraction of the main quake can be estimated at about 400 km. Overall, 428earthquakes in the region of Honshu wereregistered at the GFZ since March 9.

By analysing over 500 GPS stations, the GFZ scientists Rongjiang Wangand Thomas Walter have found that horizontal displacements of up to five metersin an eastern direction occurred at the east coast of Japan. The cause lies in the earthquake zone,i.e. at the contact interface of the Pacific plate with Japan. Computersimulations of this surface show that an offset of up to 25 meters occurredduring the earthquake.

Calculations of the GFZ modeling group headed by Stephan Sobolev evenyielded a displacement of up to 27 meters and a vertical movement of sevenmeters. This caused an abrupt elevation in the deep sea, and thus triggered thetsunami. The images of the GPS displacement vectors and the computersimulations can also be found among the online material provided by the GFZ.

Already shortly after the quake AndreyBabeyko and Stephan Sobolev of the GFZ modeled the propagation and wave heightsof the tsunami in the Pacific over the first 16 hours.

The tremendous force of the earthquake is highlighted here, too: in theopen Pacific, relatively large wave heights of over one meter were calculated,which agrees very well with the observations. How high the tsunami is piled upon the coast is largely determined by water depth and the shape of thecoastline. The GFZ material also contains an image and an animation regardingthis work.

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