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Testing the physical parameters of short baseline tiltmeters intended for earthquake prediction

M. J. Johnston
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Abstract

A program is outlined for determining the stability, linearity and calibration accuracy of short baseline tiltmeters intended for use in monitoring crustal deformation in seismically active regions. This series of tests has been performed on several different tilt instruments in order to estimate the magnitude of spurious instrument effects likely to occur in field installations. Only for short term rapid tilts (<24 hours) in a constant temperature environment (<0.01°c variation) could all instruments tested maintain <10 -8 radians electronic and mechanical stability. Thermal response ranged from 10 -6 / °C to 10 -8 / °C. To determine stability, instruments were suspended, with viscuous damping, on thin stainless steel wires, providing decoupling from all local and regional tilts. A tilt table reading to 10 -9 rad. with a dynamic range of 10 -3 rad. was used to calibrate and determine linearity of the meters.

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BibTeXRIS

M. J. Johnston. 1976. Testing the physical parameters of short baseline tiltmeters intended for earthquake prediction. https://doi.org/10.3133/ofr76556

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