The 8.9 magnitude Sendai earthquake and resulting tsunami that struck Japan just east of the island of Hoshu today has resulted in a slew of mapping resources to help understand the geography of this natural disaster and coordinate the response.
Japan Earthquake Map Viewer – Researchers at Texas Tech’s Center for Geospatial Technologies has created a ArcGIS Viewer with Flex mapping application that maps the locations of near real-time aftershocks.
Japan Sendai Earthquake Data Portal – Data portal launched by the Harvard Center for Geographic Analysis to “support the exchange of geospatial datasets for relief and reconstruction efforts.”
Earthquake Tohoku area in Japan 3/11 – local Ushahidi created by Shu Sigashi, a member of the OpenStreetMap Foundation in Japan.
USGS earthquake near the coast of Hoshu page – contains summary information, maps, and technical information about the earthquake.
OpenStreetMap’s 2011 Sendai Earthquake wiki page
Esri’s Japan Incident Map – Esri also issued a press release about their involvement:Â Esri Assists Japan Earthquake and Tsunami Response
Google’s Sendai Earthquake Map – map with layers that can be toggled on and off including USGS shakemap, earthquake and aftershock locations, shelter locations, and earth’s tectonic plates. Â All layers have a KML download link.
Earthquake Related Tweets – Sendai earthquake related tweet map created by Virender Ajmani.  (Via Google Earth Blog)
Pacific Tsunami Warning Center – geolocated warnings from NOAA’s National Weather Service.
Map Visage – each marker on this Google Map lists the location and anticipated time of arrival for the tsunami.
NOAA Tsunami Wave Height Model – also check out the animation view. (Via @cageyjames)
Google has set up a “2011 Japanese Earthquake and Tsunami” page as part of their Google Crisis Response effort which lists resources, access to their People Finder application, and streaming news and twitter feeds.