Seismic wave propagation recorded on High-Sensitivity seismograph network (Hi-net).
“Earthquake Research Institute, University of Tokyo”

The maximum acceleration (PGA) of the earth surface was set up by using Hi-net observation data (Note that the seismograph near the focal region is saturated, and the value is not accurate). A strong acceleration of over 200 cm/s/s was observed in a broad area of 500km from the mid-Iwate to Ibaraki coast which is near the focal region.

The ground acceleration is decaying drastically on the west side at the border of Itoigawa-Shizuoka Tectonic Line. It suggests that the wave attenuated at around this area. (Click the left image to see the animation)

(By: Dr.Furumura and Dr.Takemura)

An visualized image of the seismic wave propagation of the off the Pacific coast of Tohoku Earthquake, using the data from 800 High-sensitivity seismograph network（Hi-net）located all over Japan. The intensity of ground motion is indicated visually with darkness of orange and its height. The shake reached Nagoya and Sapporo after 150 sec, and by this time, data transmission from all around Tohoku area was lost. Therefore there are no data for Fukushima, Yamagata, Miyagi, Akita, Iwate Prefectures.

And then, the shake reached Wakkanai in 200 sec, further on to Ōsumi Peninsula in 300 sec, and then the whole Japanese archipelago were shaken for more than few minutes.

The strong ground motion due to the earthquake reached Oshika Peninsula in 35 sec from origin time, and in 40 sec Kesennuma to Sendai, in 50sec from Kamaishi to Iwaki and then propageted throughout the whole region of North-East Japan in 70 sec.
Usually, an animation of a seismic wave propagation is made using the strong motion waveform of K-NET, KiK-net, but this time, the data from NIED is not released because of the earthquake, so for now it is created using Hi-net. (It is reactivated at 19:00 on 13th)

Other than NIED, the data of Hi-net is delivered to ERI and JMA, via distinct line.