Abstract
In this paper, we propose our idea to open up a new field in seismology. Many practical seismometers developed up to now do not perform satisfactorily enough to record long period movements (1∼60sec) in the case of great earthquakes.
In more recent times gyroscopic instruments have been used for various purposes where limited accuracy is required.
We pay attention to the essential properties of a gyroscope such as the precession and the gyroscopic reaction moment, and propose a new instrument as a precise seismometer with a dynamic long period pendulum (proper period 2, 10, 20min) using gyroscope.
In this observation system, we utilize a vertical gyro-pendulum (transducer). The horizontal seismological movements transferred to the torque cause the gyro-axis to precess about the mutually perpendicular axes, and the precessional velocities are measured by rate-gyroscopes (measuring instruments) as amplifiers.
We examine the various dynamical characteristics as a seismometer for practical use and present technical considerations for the future development. The results obtained by the above considerations suggest that the accuracy of measurement is further improved by our new instrument.
