A large scale of apparent sudden movements in Japan detected by high-rate GPS after the 2011 Tohoku Mw9.0 earthquake: Physical signals or unidentified artifacts?

Earth, Planets and Space

Table 1 Statistics of the three components of sudden displacements from the 1198 GEONET stations between 14:59:45 and 14:59:46 after the 2011 Tohoku earthquake

Measures	East component	North component	Vertical component
Number of stations	796	794	913
Percentage (GEONET)	66.44	66.28	76.21
Percentage (northeastern)	65.59	69.35	76.88
Mean values (mm)	− 2.43	2.83	− 4.75
Standard deviations (mm)	2.02	2.17	5.00

The first row lists the numbers of stations to move westward, northward and downward, respectively. The next two rows list the percentages of displacements from the whole GEONET network and the northeastern Japan, respectively. The percentages in the vertical component are referred to downward movement. The fourth row lists the mean values of displacements in the east, north and vertical directions. The last row gives the robust adaptive mean values of standard deviations of displacements between two consecutive epochs, as computed from the 30 min of GEONET GPS data before the earthquake