Large portions of the Japan Quake hit coastline may be uninhabitable

Last update: March 22, 2011 at 6:14 pm by By

Snow covered fields and inundated land

Agricultural fields lies between the Japanese city of Sendai and Sendai Bay, and the area was one of the hardest hit by the tsunami on March 11, 2011. The Advanced Land Imager (ALI) on NASA™s Earth Observing-1 (EO-1) satellite captured this natural-color image of the area on March 18, 2011.

One week after the magnitude-9.0 earthquake and resulting tsunami, the fields nearest the ocean were still covered with standing water. It is possible that some areas could remain that way, as the ground level sank along the east coast of Japan during the earthquake. The same tectonic forces that lifted up the seafloor to create the tsunami also caused land to subside on the mainland.

On the outskirts of the Sendai suburbs, fields that had escaped inundation or had already drained were later covered with snow, as was much of the Sendai metropolitan area when a cold front brought winds and snow to northeastern Japan. The iced highways hampered search-and-rescue efforts and added to the misery of 500,000 evacuees, reported Agence France-Presse. In some places, the snow was heavy enough to add dangerous weight to already damaged buildings. According to aid groups, however, most of the quake and tsunami survivors had access to adequate shelter, water, food, and medical attention.

Unfortunately for the displaced, harsh weather was expected to continue. As of March 19, 2011 (Japanese time zone), forecasts from Japan™s Meteorological Agency called for continuing cold temperatures along with rain or snow for much of the country over the next week. The forecast for Sendai included low temperatures and high probabilities of rain.

A view on Earthquake Intensity in the Quake hit areas

The earthquake shook buildings and damaged infrastructure hundreds of kilometers away. Closer to the main shock, coastal regions were devastated by the quake and the resulting tsunami.

This map shows the ground motion and shaking intensity from the earthquake at dozens of locations across Japan. Each circle represents an estimate of shaking as recorded by the USGS, in conjunction with regional seismic networks. Shades of pale yellow represent the lowest intensity and deep red represents high intensity. The ground shaking data is overlaid on a map of population density provided by Oak Ridge National Laboratory.

A shaking intensity of VI is considered œstrong and can produce œlight damage, while a IX on the scale is described as œviolent and likely to produce œheavy damage.
The pattern of shaking appears to run parallel to the offshore subduction trench, with the intensity decreasing more from east to west, as opposed to north and south. Ground motion also seems to be more intense in coastal and riverine areas, where settlements are built on softer sediments and less bedrock.

Note the number of VIIs and VIIIs near Tokyo, well away from the epicenter; the lack of a severe human toll in that metropolitan area is surely a testament to the quality of the nation™s earthquake preparedness.

Images and text : NASA Earth Observatory

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