For many years, seismological research mainly focuses on translational ground motions due to the lack of appropriate sensors. However, because of the development of devices based on Sagnac effect, measuring rotational waves directly comes available. In this work, a portable three-component broadband rotational seismometer named RotSensor3C based on open loop interferometric fiber optic gyroscope (IFOG) is designed and demonstrated. Laboratory tests and results are illustrated in detail. The self-noise ranging from 0.005 Hz to 125 Hz is about 1.2×10−7rads−1/Hz, and with the harmonics compensation the scale factor variation over ±250∘/s is lower than 10 ppm (parts per million). The misalignment matrix method is adopted to revise the output rotation rate. In a special near field experiment using the explosive source, the back-azimuths and phase velocity are estimated by the recorded acceleration and rotation rate. All the results prove the practicability of this new rotational sensor.

Most of the previous seismic observation and analysis are still focused on the application of three orthogonal translation components. Because of lack of records of rotational motion, the seismic wavefield can not be completely described. We use an A-SM-2km rotation seismograph directly measure the rotation signals of ground motion and analyz them by short-time Fourier transform. The results show that the characteristic of the rotating component as the station spacing increase presents high-frequency attenuation.