Starting with descriptions of rotational seismology, areas of interest and historical field measurements, the fundamental requirements for rotational seismometers for seismological and engineering application are formulated. On the above basis, a review of all existing rotational seismometers is presented with a description of the principles of their operation as well as possibilities to fulfill formulated requirements. This review includes mechanical, acoustical, electrochemical and optical devices and shows that the last of these types are the most promising. It is shown that optical rotational seismometer based on the ring-laser gyroscope concept is the best for seismological applications, whereas systems based on fiber-optic gyroscopes demonstrate parameters which are also required for engineering applications. Laboratory results of the Fibre-Optic System for Rotational Events & Phenomena Monitoring using a small 1-D shaking table modified to generate rotational excitations are presented. The harmonic and time-history tests demonstrate its usefulness for recording rotational motions with rates up to 0.25 rad/s.

Interest in measuring displacement gradients, such as rotation and strain, is growing in many areas of geophysical research. This results in an urgent demand for reliable and field-deployable instruments measuring these quantities. In order to further establish a high-quality standard for rotation and strain measurements in seismology, we organized a comparative sensor test experiment that took place in November 2019 at the Geophysical Observatory of the Ludwig-Maximilians University Munich in Fürstenfeldbruck, Germany. More than 24 different sensors, including three-component and single-component broadband rotational seismometers, six-component strong-motion sensors and Rotaphone systems, as well as the large ring laser gyroscopes ROMY and a Distributed Acoustic Sensing system, were involved in addition to 14 classical broadband seismometers and a 160 channel, 4.5 Hz geophone chain. The experiment consisted of two parts: during the first part, the sensors were co-located in a huddle test recording self-noise and signals from small, nearby explosions. In a second part, the sensors were distributed into the field in various array configurations recording seismic signals that were generated by small amounts of explosive and a Vibroseis truck. This paper presents details on the experimental setup and a first sensor performance comparison focusing on sensor self-noise, signal-to-noise ratios, and waveform similarities for the rotation rate sensors. Most of the sensors show a high level of coherency and waveform similarity within a narrow frequency range between 10 Hz and 20 Hz for recordings from a nearby explosion signal. Sensor as well as experiment design are critically accessed revealing the great need for reliable reference sensors.

Surface rotational ground‐motion records that were collected by a network of deep mining exploration monitoring in the Polish region of the Upper Silesian Coal basin are reported. A set of 51 rotation records acquired during the first two months of the recording program is analyzed. The three strongest records are discussed in detail in this article. Thus far, the maximum measured rotation velocity has reached 0.03°/s, whereas the respective maximum rotational acceleration was equal to 2.53°/s2. Based on the maximum horizontal ground velocity of 2 cm/s, this corresponds to the modified Mercalli intensity (MMI = IV). The recorded “time history” records of ground rotations have similar durations to those of their respective translational records. However, their Fourier spectra are shifted to higher frequencies in a characteristic way, as predicted by earlier, theoretical considerations. The long‐term objective of the research program is to acquire robust surface rotation records that correspond to MMIs VI or even VII, since mine tremors with a magnitude of 4 or higher are expected to occur in this area in the near future.

The case study presents an assessment of the traffic-induced vibrations on humans and residential buildings, which is important for sustainable development. The analyzed residential building had several cracks in the walls. Control gypsum tapes were applied to all cracks in the building and additional elements near the road to determine the propagation of the damage. To determine the harmfulness of vibrations for humans, vibration acceleration measurements linked to road traffic inside the analyzed building were carried out. The vibration velocities inside the object were set based on the integration of the obtained accelerations. The experimental field investigation was carried out in places where humans commonly stayed (on the first floor) at the points where the vibrations are transmitted from the construction to humans. The study involved a time history analysis, a Fast Fourier Transform (FFT) analysis, and Root Mean Square (RMS) acceleration and velocity in a one-third octave bands spectrum. Based on the conducted experimental tests, it can be pointed out that the received velocity values in the tested building, caused by the passage of various vehicles, were below the permissible levels. However, it was noticed that the distance between the building and the fence had an important role in damping vibrations emitted by passing vehicles. The presented case study may be of use to other researchers who will be involved in similar cases and want to include sustainable infrastructure development.

Preliminary results of an application of rotation rate sensors in dynamic identification of a vibrating beam are reported. Three rotational sensors, measuring the response of a cantilever beam to kinematic harmonic excitations are applied in the reconstruction of its stiffness. A successful reconstruction of 15% stiffness drops is demonstrated. With the development of angular sensors and the decrease in their cost one can expect further progress of this new area of vibration-based damage detection.