The Development of a New IFOG-Based 3C Rotational Seismometer

Abstract

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.

Perspective chapter: Application of gyroscopes in geophysics

“…Rotational seismometers are critical in capturing and analyzing the rotational components of ground motion during seismic events. The core of a rotational seismometer lies in its angular velocity sensor (i.e., gyroscope), which comes in various types, such as mechanical gyroscopes [17], MEMS (Micro-Electro-Mechanical System) gyroscopes [18], electrochemical gyroscopes [19], laser gyroscopes [20], and FOGs [21][22][23]. Based on actual observation cases, researchers at Ludwig-Maximilians University specified the following a priori requirements of seismic rotational sensors [24]:…”

Correction for phase-generated carrier algorithm demodulation errors caused by uneven frequency response

“…It artificially introduces a high-frequency phase carrier signal and shifts the measured signal to the high-frequency carrier sidebands, and thus suppresses most low-frequency disturbances [4]. Therefore, the PGC algorithm has exhibited remarkable performance in detecting weak signals, which has engendered its extensive utilization within the realm of optical fiber sensors [5,6].…”

Six‐Component Earthquake Synchronous Observations Across Taiwan Strait: Phase Velocity and Source Location

“…Ring Laser Gyroscopes (RLG) have the highest sensitivity, and can observe the teleseismic signals (Belfi et al., 2017; Igel, 2005; Igel et al., 2021; Schreiber et al., 2009; Simonelli, et al., 2016). Fiber optical seismometers have the characteristics of high sensitivity, wide frequency band and portability, and are widely used in the observation of earthquakes and volcanic seismology (Bernauer et al., 2018; Cao et al., 2021; Eibl et al., 2022; Izgi et al., 2021). On the other hand, rotational seismic observation has put forward higher requirements for environmental noise.…”