The Yomiuri Shimbun
The seabed near the focus of the March 11 earthquake off Miyagi Prefecture moved about 24 meters east-southeast as a result of crustal movement during the massive temblor, the Japan Coast Guard announced Wednesday.
An earlier survey by the Geospatial Information Authority of Japan showed the Oshika Peninsula in Ishinomaki in the prefecture moved about 5.3 meters east during the earthquake.
The coast guard survey showed crustal movement at a depth of about 1,700 meters and about 120 kilometers off the Oshika Peninsula was more than four times the observed shift of the peninsula itself.
On March 28 and 29, a JCG surveying ship checked a total of eight location markers set in the seabed. It discovered seven of them had moved about 24 meters east-southeast, and the seabed had risen about three meters.
A location marker set in the seabed about 80 kilometers off Fukushima Prefecture had moved about five meters east-southeast.
According to the JCG, a magnitude-7.2 earthquake in August 2005 off Miyagi Prefecture caused the seabed to move about 10 centimeters. The March 11 earthquake measured magnitude-9.
A coast guard official said, "The amount of crustal movement we saw this time is unprecedented in recorded history."
(Apr. 8, 2011)
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