Developments in new fluid rotational seismometers: instrument performance and future directions

0464249 - GFÚ 2017 RIV US eng J - Journal Article
Evans, J. R. - Kozák, Jan - Jedlička, Petr - Jedlička, Z.
Developments in new fluid rotational seismometers: instrument performance and future directions.
Bulletin of the Seismological Society of America. Roč. 106, č. 6 (2016), s. 2865-2876. ISSN 0037-1106. E-ISSN 1943-3573
R&D Projects: GA MŠMT(CZ) ME10008
Institutional support: RVO:67985530
Keywords : ground motions * sensors * seismology
Subject RIV: DC - Siesmology, Volcanology, Earth Structure
Impact factor: 2.146, year: 2016

In this article we describe prototype designs and tests for low-cost rotational medium-and strong-motion seismometers using three types of proof mass (two liquid and one solid) and a number of transducer configurations. This article describes the third set of designs and tests in our development program. The details of our results for most of these are in the sic electronic supplement to this article, whereas here we concentrate on three of the most promising and representative design combinations. Most of our results pertain to sensors with water or silicon oil as the proof mass, though we also tested a torsion-bar design with a solid proof mass. We find that most mass-transducer combinations lead to output proportional to rotational acceleration, with varying degrees of fidelity. Most combinations we tested can be dismissed from further development for reasons of performance or inconvenience during analysis of acceleration response (compare with sic electronic supplement). In this article, we describe three of the more promising combinations, one each for the three types of response functions we measured. Of these three, one mass-transducer combination in particular (a hinged sensing element and capacitive transduction) has output voltage closely proportional to rotational displacement (angle) over a wide frequency range; such displacement proportionality obviates two of the integration steps normally required to solve for continuum single-point motions or correct for tilt-induced errors in horizontal translational sensors. Thus, although we illustrate two other designs of some promise, we propose a new design that follows this displacement-proportional path while increasing the device's sensitivity to on-axis rotations, improving its manufacturing ease and lowering its sensitivity to translational motions.
Permanent Link: http://hdl.handle.net/11104/0263215