My thanks to Dr. David Wald with the USGS in Golden, Colorado, who was kind enough to respond to my inquiry about the direction of Japan’s main-island shift as a result of the earthquake. He also answered another question regarding Japan’s elevation. His reply:
“First, Japan shifted towards North America (eastward). Japan deformed during the earthquake, so the east coast of Japan moved a lot more than the west coast. Yes, also to the elevation issue. The east coast of Honshu dropped a few feet, again variable with location (not all of Japan dropped). This would have contributed to the inundation since the coast dropped before the tsunami reached shore.”
I could not find this information anywhere online, so I’m grateful for Dr. Wald’s taking the time to reply. You can bet the USGS is extremely busy these days.
So in answer to a reader’s inquiry, it seems that at least along the coast in one particular area, Japan did lose elevation. We’ll learn more in days to come, but I suspect it’s a result of plate subduction, and a particularly tragic result at that. As Dr. Wald pointed out, the coast dropped before the tsunami struck, which was particularly bad timing and bad luck for the villagers along that coastal area.