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fröstel's Diary

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Comment from z-dude on 16 March 2011 at 01:37

Just the coastline moved, according to that report. So the north shore stayed the same, and a the coastline in the earthquake affected area moved.

A lot of OSM coastlines weren't that accurate to begin with. The trick to accurate armchair mapping is having accurate ortho photos to trace from.. but the orthophotos may have been laid over top of the old streetmap. It would be a bit tricky to get a GPS trace from a shoreline cliff.
The best bet would bet to get orthophotos, and calibrate them to some reference gps tracks. ie, slowly use your GPS and walk in a circle which is quite visible from the ortho photos (ie, around a fountain)

There is an Disaster Mapping project on OSM, called HOT, the Humanitarian OpenStreetMap Team osm.wiki/HOT

According to HOT, the Japan OSM Team is coordinating the mapping.
osm.wiki/wiki/2011_Sendai_earthquake_and_tsunami

Comment from fröstel on 16 March 2011 at 01:42

The shift was measured with local GPS stations. So I assume when these strutures have moved, then everything around them has moved as well, roads, forests, lakes, rivers, etc. Of course this doesn't apply to all of japan in unison, but the shift varies regionally.

Comment from fröstel on 16 March 2011 at 01:42

The shift was measured with local GPS stations. So I assume when these strutures have moved, then everything around them has moved as well, roads, forests, lakes, rivers, etc. Of course this doesn't apply to all of japan in unison, but the shift varies regionally.

Comment from seav on 16 March 2011 at 12:21

The same thing happened in the 2010 Chile earthquake. Parts of Chile moved several feet to the west. I'm not sure if the plate's movement was accounted for in mapping Chile since the earthquake. A problem is that satellite imagery tend to be aligned with respect to older imagery.

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