Publication Date:
2015-11-20
Description:
Fiber-based interferometers provide the means to sense very small displacements over long baselines, and have the advantage of being nearly completely passive in their operation, making them particularly well suited for geophysical applications. A new 250 m, interferometric vertical borehole strainmeter has been developed based completely on passive optical components. Details of the design and deployment at the Piñon Flat Observatory are presented. Power spectra show an intertidal noise level of −130 dB (re. 1 ϵ 2 /Hz), consistent within 1–3 dB between redundant components. Examination of its response to Earth tides and earthquakes relative to the areal strain recorded by an orthogonal pair of collocated, 730 m horizontal laser strainmeters yield a Poisson’s ratio for local near surface material of 0.25 that is consistent with previous results.
Print ISSN:
0034-6748
Electronic ISSN:
1089-7623
Topics:
Electrical Engineering, Measurement and Control Technology
,
Physics
Permalink
