*Takumi Hayashida1, Hiroto Nakagawa1, Toshihide Kashima1
(1.International Institute of Seismology and Earthquake Engineering, Building Research Institute)
Keywords:geotechnical centrifuge, Ground motion, MeSO-net, Surface wave
In the southern part of Ibaraki Prefecture, remarkable signals with a single peak in 1–2 Hz are occasionally observed. Acceleration records measured at the Building Research Institute (BRI) show dominant signals lasting for several hundred seconds. The cause of this signal is thought to be the force generated by a geotechnical centrifuge in a nearby facility, and the estimated dominant frequency based on the turning radius and centrifugal acceleration of the equipment coincides with that of the signal. We detected these signals using the continuous acceleration data recorded at BRI and MeSO-net stations of the National Research Institute for Earth Science and Disaster Prevention (NIED) to investigate the spatial range of signal propagation. The signals were observed over a wide area, especially in Tsukuba, where the source is possibly located. The signal could be used to identify and monitor the seismic wave velocity of the subsurface sediments or to investigate the dynamic characteristics of buildings having the same natural frequency. We report the spatio-temporal characteristics of the detected signals and examples of signal measurements in a building that may cause resonance.
Acknowledgments:
We used MeSO-net seismic data provided by the National Research Institute for Earth Science and Disaster Resilience (NIED). We would like to express our gratitude to Dr. Haruhiko Suzuki (OYO corporation) for his advice in the conception of this study.