Caltech says the northern part of Japan was pushed eastward about 2 feet in this week's quakes. (Caltech)
Caltech professor Mark Simons describes the movement of the island of Japan. (Matt Schrader)
Japan’s earthquake and aftershocks have moved the entire island about 60-70 centimeters into the Pacific Ocean, Caltech officials said Saturday — equivalent to about 23-28 inches.
“The entire Island of northern Japan moved out toward the ocean,” said Caltech geophysics professor Mark Simons.
Simons said the movement was due to the alternating pressure on different plates after a major earthquake.
“After you have a large kick to the system,” said Simons, “the entire system starts to recalibrate.”
He said, however, that aftershocks are beginning to subside.
“The aftershocks are behaving normally and that means decaying with time,” he said.
The data gathered in the Friday’s 9.1 megaquake in Japan is the most recorded earthquake in history due to Japan’s intricate measurement system in place, officials said.
“There’s a lot of unknowns and surprises with earthquakes,” said Simons. “These observations are coming in and being processed and being reprocessed and will be used to develop an actual model.”
The reason Friday’s quake took so many by surprise was because, although Japan lies in the middle of the world’s busiest tectonic plates, most of the activity is significantly smaller, and often goes completely unnoticed by many in Japan.
“This has always been recognized to be one of the world’s great subduction zones,” said Lucy Jones of the U.S. Geological Survey. “In Japan, when people looked at this great fault, they saw they have no records of great earthquakes.”
“The deduction was that it must be slowly creeping along,” said Caltech professor Tom Heaton. “Now we see a truly giant earthquake on it’s own, and we’re just trying to investigate what has happened.”
More than 200 earthquakes have occurred over the past week, in addition to Friday’s 9.1 megaquake, according to officials.
“We have recorded 200 earthquakes of magnitude 5 or larger in this sequence,” Jones said. “We’ve had about 30 magnitude 6’s.”
