Performance of Several Low-Cost Accelerometers

J.R. Evans, R.M. Allen, A.I. Chung, E.S. Cochran, R. Guy, M. Hellweg, and J.F. Lawrence, U.S. Geological Survey, University of California, Berkeley, Stanford University, California Institute of Technology Seismo. Res. Lett. , 85, 147-158 doi: 10.1785/0220130091, 2014. Download a reprint: EvansEtAl-ClassCSensors-SRL-2014.pdf

Figure 7. Operating ranges for the tested sensors range from the noise floor (half-octave total rms) to the clipping level (rms of just- clipping 2g sine). Box-like features are caused by integrating to half-octaves narrowband peaks, which are of little impact to sensor performance. All sensors roll off at their anti-alias corners, set by their sample rates; the Phidget has the highest such corner because of its high-sampling rate. Large-Event Examples are at the peak amplitude (times 0.707 for comparison to rms noise) and span the half-width of their spectrum.

Introduction
Several groups are implementing low-cost host-operated systems of strong-motion accelerographs to support the somewhat divergent needs of seismologists and earthquake engineers. The Advanced National Seismic System Technical Implementation Committee (ANSS TIC, 2002), managed by the U.S. Geological Survey (USGS) in cooperation with other network operators, is exploring the efficacy of such systems if used in ANSS networks. To this end, ANSS convened a working group to explore available Class C strong-motion accelerometers (defined later), and to consider operational and quality control issues, and the means of annotating, storing, and using such data in ANSS networks. The working group members are largely coincident with our author list, and this report informs instrument-performance matters in the working group’s report to ANSS. Present examples of operational networks of such devices are the Community Seismic Network (CSN; csn.caltech.edu), operated by the California Institute of Technology, and Quake-Catcher Network (QCN; Cochran et al., 2009; qcn.stanford.edu; November 2013), jointly operated by Stanford University and the USGS. Several similar efforts are in development at other institutions. The overarching goals of such efforts are to add spatial density to existing Class-A and Class-B (see next paragraph) networks at low cost, and to include many additional people so they become invested in the issues of earthquakes, their measurement, and the damage they cause.