Study on Estimation of Direction Error of KiK-Net Surface Seismograph

Osamu Tsujihara

Department of Civil Engineering, Wakayama National College of Technology, Wakayama, Japan.


National Research Institute for Earth Science and Disaster Prevention deploys the digital strongmotion seismograph (KiK-net) which includes about 700 observation sites across the all of Japan. Each station of KiK-net has six channels of strong-motion seismograph. The sensors of 1–3 and 4–6 channels are installed at the bottom of the borehole and on the ground surface, respectively. The sensors of 1 and 4 channels are installed in the North-South direction and the sensors of 2 and 5 channels in the East-West direction. It is known that there is a slight misalignment in the directions of borehole sensors. However, the seismograph installed on the ground surface reportedly has also the direction error at some stations. In this research, the direction errors of installation of seismograph on the ground surface were estimated at 623 stations by the correlation of the long-period components of between 1 and 4, and between 2 and 5.

Keywords: Seismograph installation direction, Identification, KiK-net.

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