Kenneth Hudnut, a geophysicist with the U.S. Geological Survey (USGS), said, “At this point, we know that one GPS station moved (8 feet), and we have seen a map from GSI (Geospatial Information Authority) in Japan showing the pattern of shift over a large area is consistent with about that much shift of the land mass.”
The quake occurred as the Earth’s crust ruptured along an area about 250 miles (400 kilometres) long by 100 miles (160 kilometres) wide, as tectonic plates slipped more than 18 meters, said Shengzao Chen, a USGS geophysicist.
Meanwhile, researchers at Texas Tech’s Center for Geospatial Technologies have created a near-real-time map of the aftershocks occurring globally following the Japan earthquake. Kevin Mulligan, Director of the centre, said, the Earthquake Viewer connects to near-real-time remote feeds from the United States Geological Survey’s Earthquake Hazards Program. It provides map information, satellite imagery and location of recent earthquakes. As part of this major earthquake, there are hundreds of aftershocks that follow. In addition, the Tsunami Viewer connects to the National Oceanic and Atmospheric Administration’s Pacific Tsunami Warning Center.
On the other hand, researchers at Geospatial Information Authority of Japan (GSI) constructed a fault model using coseismic surface displacement data observed by GEONET, indicating that the displacement occurred in two rectangular faults with the following characteristics:
- A total major rupture length of ~400 kilometres with a fault width of ~80—90 kilometres. (northern segment: ~200 kilometres / southern segment: ~180 kilometres)
- A fault upper edge at a depth of 10 kilometres
- A reverse fault motion is inferred. Slip amounts of northern segment and southern one are estimated to be ~28 meters and ~6 meters, respectively
- A total moment magnitude is 8.8. (northern segment: Mw8.7 / southern segment: Mw8.2).
Sachiye Day, VERTICES intern. firstname.lastname@example.org