Rotational Seismometer

Tellus R is the basis for constructing the most modern seismic systems, recording all 6 components of mechanical motion.

It has a high sensitivity for the detection of rotational modes of earthquakes, a wide dynamic and frequency range.

A characteristic feature of Tellus R is low noise with minimal power consumption, which is a significant advantage over electro-mechanical, fiber-optic and other types of rotational motion sensors. This device has a calibration input, which allows to perform periodic calibration without use of special expensive equipment. The device is capable of operating at any orientation in space over a wide range of temperatures.

Rotational Seismology is an emerging study of all aspects of rotational motions induced by earthquakes, explosions and ambient vibrations.

To describe the situation during vibration generated by an earthquake, the general motion of particles or a small volume in a solid body, can be divided into three parts: translation (along the x, y, and z axes), rotation (about the x, y, and z axes), and strain (e.g. Båth, 1979; Teisseyre et al., 2006).

Rotational ground motion has been ignored for centuries due to a widespread belief that rotation is insignificant in measuring it but recently it is believed that rotational signals may contain additional valuable information for studying wave propagation; in addition, rotational ground motion may be important in the excitations of certain engineering structures.

According to the introduction to a special issue of the Bulletin of the Seismological Society of America, rotational seismology has become an emerging field for the study of all aspects of rotational ground motion induced by earthquakes, explosions, and ambient vibrations. This domain has attracted the attention of researchers from a wide range of geophysical disciplines and structural engineers.

ChannelsXYZ Rotational
Resolution6*10-8 rad/s at 1 Hz
Output Signal+/- 20 V differential, 0.4 rad/s
Dynamic Range117dB
Selfnoise PSD-125dB (rel. 1 rad/s2/√Hz)
Frequency range0.033 – 50 Hz (opt. 0.01 – 100 Hz)
Generator Constant50 V/rad/s
Mass Centeringnone
Installation Angleany
Calibration Input1:1
Power Supply10-18VDC
Power Consumption30 mA
Dimension180mm OD Height 140mm
Op temp-15 to + 55 C (opt. -40 to + 55 C)
HousingAnodized Aluminium
Cable3m standard or custom