News from the Geospatial Information Authority of Japan (GSI) confirms that the 9.0 magnitude Tohoku earthquake caused a severe horizontal displacement. Japan’s GPS Earth Observation Network System (GEONET), which has 1,200 permanent monitoring stations, has provided a detailed view of between a 6 and 28 meter shift along two fault blocks totaling 400 kilometers long. With such a large displacement, what are some of the geospatial implications of such a shift?

Remapping Needed

Given the implications of such a large shift over such a large area, a remapping effor is warranted. The location of assets are the primary items to be remapped, especially for engineering-grade projects dealing with construction and rebuilding infrastructure. The displacement is also quite severe as to have an impact on navigation, although the distances are well below the tolerances needed for wayfinding.

Ocean Navigation

The change of topography underwater is a critical issue, because there are no assurances that navigational channels are clear without bathymetric surveys to understand how subsurface features have changed. There can be no assumptions here as the offshore epicenter and great magnitude of the quake have likely had a big impact on the seafloor.

Property Lines

Mapping of property boundaries, which are tied to control points, are going to be off.  Serious delays to rebuilding occurred after the 1995 earthquake in Kobe, Japan due in part to complicated property laws that obscure ownership. Given high land-sales taxes, it is common for the land under any given structure to consist of plots owned by different owners. It's understandable that the two levels of stakeholders – landowners and building owners – would have difficulty agreeing on whether or how to rebuild. Hopefully, the complications of land displacement and property ownership won’t stand in the way of a quick recovery in this devastating disaster.