Hi All. It is now almost 5:00 Saturday afternoon in Japan and more news coming in. It appears the city of Sendai was hard hit. The injury rate there is 300. No deaths have been reported so far.

Some houses are flat. The only things you can see sticking up in the air are the roofs. The walls are gone. It doesn’t appear that any of the larger buildings sustained very much in the way of structural damage, but boy, what a mess inside. Books, papers, filing cabinets, computers etc. laying all over the place. Why no body was killed is beyond me.

A couple of roads are now closed due to damage. One road appears to have been cut in half. Some city streets are closed due to water lines being broken under the streets causing the streets to cave in.

In an open area not to far from the city the ground appears to have sunk between 5 and 6 feet in some locations. Not sure if this is where the fault is located or is the results of a slide. The last large quake in this area was an M>5.9 on11/27/1993. This is about 13 miles north of the most recent quake.

An earthquake offshore of northeast Japan on July 13, 869 produced a large-scale tsunami that damaged the low-lying coastal zones of northeast Japan. This 869 tsunami, named the Jogan tsunami after the reign of then emperor, is unusual because of its widespread flooding. The historical document Sandai-jitsuroku, which gives a detailed history of all of Japan for 1200 years, describes the Jogan earthquake and subsequent tsunami as follows:

“The large earthquake was accompanied by a luminous phenomenon, and coastal areas were illuminated in the dark. Some time after severe seismic shocks, a gigantic tsunami reached the coast and invaded the entire Sendai plain. Rising seawater flooded an old castle town, causing the loss of 1000 lives.”

There is no historical evidence of co-seismic subsidence of the plain (Usami, 1987); therefore the prolonged period of flooding indicates that waves from the Jogan tsunami sequentially invaded the coastal areas. Destroyed structural foundations that date from the 8th and 9th centuries, discovered in the ruins of Tagaj, are overlain by sediment layers containing artifacts from the middle 10th century.

Recent GPS observations (Nishimura et al., 2000) show that the plate boundary is being shortened by east-west compression and strain energy accumulating offshore Sendai. Some past earthquakes have generated tsunami with waves several meters high (Watanabe, 1998). Hatori (1987), who studied many old documents recording historical offshore earthquakes, estimated that the magnitude of the1793 Kansei earthquake was about 8.2. He judged that the 1611 Keich tsunami that invaded the coastal area of the Sendai plain was caused by an 8.1 magnitude earthquake. The type of crust deformation and mode of fault movement depend on the tectonic processes. If two sets of fault movement are linked in the accretionary wedge (Growth or increase in size by gradual external addition, fusion, or inclusion.) it is probable that the magnitude will be 8.0 or more offshore Sendai (Earthquake Research Committee of the Japanese Government, 2000)

Being as how the M>6.2 quake was a thrust quake and the M>5.3 quake that occurred earlier was a strike-slip with thrust faulting component it is more then likely these quakes are the results of the compression. None of the most recent quakes have released enough energy to reduce the probability of a major, or great quake. Take Care…Don in creepy town