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A seismic sensor is an instrument to measure the ground motion when it is moved by a perturbation. This motion is dynamic and the seismic sensor or seismometer also has to give a dynamic physical variable related to this motion.
The motion of the ground is generally measured in the xyz directions so three sensors are needed. The theoretical description is the same for the three sensors while the construction methods might be different. For special applications, ground rotation is also measured.
Our objective is to measure the ground motion at a point with respect to this same point undisturbed. The main difficulties of this are:
The measurement is done in a moving reference frame, in other words, the sensor is moving with the ground and there is not any fixed undisturbed reference available. According to the inertia principle, we can only observe the motion if it has an acceleration.
The amplitude and frequency range of seismic signals is very large. The smallest motion of interest is the ground noise, which carries information and might be as small as 0.1 nm, and the largest motion near a causing fault could be 10 m. This represents a dynamic range of (10/10−10) = 1011. Similarly, the frequency band starts as low as 0.00002 Hz (earth tides) and could go to 1000 Hz. These values are of course the extremes, but a good quality all round seismic station for local and global studies should at least cover the frequency band 0.01–100 Hz and ground motions from 1 nm to 10 mm.
It is not possible to make one single instrument covering this range of values in both frequency and amplitude and instruments with different gain and frequency response are used for different ranges of frequency and amplitude.
Sensors are divided into passive and active sensors. A passive seismometer essentially consists of a swinging system with a signal coil that outputs a voltage linearly proportional to the ground velocity at frequencies above the natural frequency f 0 . No electronics is involved, however there is a lower limit to f 0 of about 0.03 Hz so a passive sensor cannot be used for very low frequencies. Passive low frequency sensors are large, heavy and expensive. Most modern sensors are active. They also have a swinging system but different kinds of electronic feedback makes it possible to make smaller sensors covering a large frequency band (typically 0.01–100 Hz) with the output linearly proportional to velocity, the so-called broad band sensors. An accelerometer works with a similar electronic feedback principle but has an output linearly proportional to acceleration in a frequency band of typically 0–100 Hz. The MEMS sensor (Micro Electro-Mechanical systems) is an accelerometer using the same principle but built into an integrated circuit so the sensor is very small. There is now a tendency for all sensors to be of the active type since the cost has come down, however passive sensors with f 0 > 1 Hz (geophones) are still produced in large numbers.
The theory for passive sensors is relatively simple, while active sensors can use very sophisticated feedback and filter techniques making the theory correspondingly complex. However, the basic response of the two types of sensors is quite similar.
All sensors will generate electronic noise, particularly active sensors, and an important aspect of sensor design is to achieve as low a noise as possible.
Different sensors are used for different purposes. The broad band sensor is used for regional and global seismology, accelerometers for strong motion networks and geophones are used for recording micro-earthquakes.
Different kinds of sensors on the market will be discussed.
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Aki K, Richards PG (1980) Quantitative seismology – theory and methods. In: Chapter 10: Principles of seismometry, vol 1. W. H. Freeman and Company, San Francisco, pp 477–524
Anderson JA, Wood HO (1925) Description and theory of the torsion seismometer. Bull Seismol Soc Am 15:1–76
ANSS Working Group on Instrumentation, Siting, Installation, and Site Metadata of the Advanced National Seismic System Technical Integration Committee (2008) Instrumentation guidelines for the Advanced National Seismic System, U.S. Geol. Surv. Open-File Rept. 2008–1262, 41 pp
Barzilai A (2000) Improving a geophone to produce an affordable, broadband seismometer. Ph. D. thesis, Stanford University. http://micromachine.stanford.edu/projects/geophones/DefenseBarzilaiFinalCopyWeb/DefenseBarzilaiFinalCopy.pdf
Barzilai A, Zandt TV, Kerry T (1998) Technique for measurement of the noise of a sensor in the presence of large background signals. Rev Sci Instrum 69:2767–2772 CrossRef
Bormann P (ed) (2002) IASPEI New manual of seismological observatory practice (NMSOP). Geo Forchungs Zentrum Potsdam, Potsdam
Brokešová J, Málek J (2013) Rotaphone, a self-calibrated six-degree-of-freedom seismic sensor and its strong-motion records. Seismol Res Lett 84:737–744 CrossRef
Byrne CJ (1961) Instrument noise in seismometers. Bull Seismol Soc Am 51:69–84
Clinton JF, Heaton TH (2002a) Potential advantages of a strong-motion velocity meter over a strong-motion accelerometer. Seismol Res Lett 73:333–342 CrossRef
Clinton JF, Heaton TH (2002b) Performance of the VSE-355G2 strong-motion velocity seismometer. Report to the IRIS-GSN Sub-Committee. Department of Civil Engineering, Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125. www.ecf.caltech.edu/~jclinton/publications/IRISREV.pdf, 30 pp
Deng T, Chen D, Wang J, Chen J, He W (2014) A MEMS based electrochemical vibration sensor for seismic motion monitoring. J Microelectromech Syst 23:92–99
Evans JR, Allen RM, Chung AI, Cochran ES, Guye R, Hellweg M, Lawrence JF (2014) Performance of several low-cost accelerometers. Seismol Res Lett 85:147–158 CrossRef
Homeijer B, Lazaroff D, Milligan D, Alley R, Wu J, Szepesi M, Bicknell B (2011) Hewlett Packard’s seismic grade MEMS accelerometer. In: Proc. IEEE 24th international conference on micro electro mechanical systems (MEMS), 2011, 23–27 Jan, Cancun, Mexico, pp 585–588. doi: 10.1109/MEMSYS.2011.5734492
Huang H, Agafonov V, Yu H (2013) Molecular electrical transducers as motion sensors: a review. Sensors 13:4581–4597 CrossRef
Igel HJ, Brokesova JE, Zembaty Z (2012) Preface to the special issue on “Advances in rotational seismology: instrumentation, theory, observations, and engineering”. J Seismol 16:571–572 CrossRef
LaCoste LJB (1934) A new type long period seismograph. Physics 5:178–180 CrossRef
Lee WHK, Çelebi M, Todorovska MI, Igel H (2009) Introduction to the special issue on rotational seismology and engineering applications. Bull Seismol Soc Am 99:945–947 CrossRef
Levchenko DG, Kuzin IP, Safonov MV, Sychikov VN, Ulomov IV, Kholopov BV (2010) Experience in seismic signal recording using broadband electrochemical seismic sensors. Seism Instrum 46:250–264 CrossRef
Li B, Lu D, Wang W (2001) Micromachined accelerometer with area-changed capacitance. Mechatronics 11:811–819 CrossRef
Liu CH, Kenny TW (2001) A high-precision, wide bandwidth micromachined tunneling accelerometer. J Electromech Syst 10:425–433 CrossRef
MacArthur A (1985) Geophone frequency calibration and laser verification. Geophysics 50:49–55 CrossRef
Milligan DJ, Homeijer B (2011) An ultra-low noise MEMS accelerometer for seismic imaging. In: Sensors 2011 IEEE, 28–31 Oct 2011, Limerick, pp 1281–1284. doi: 10.1109/ICSENS.2011.6127185
Millman J (1987) Microelectronics: digital & analog circuits & systems. McGraw-Hill Education, New York, 996 pp
Nigbor RL, Evans JR, Hutt CR (2009) Laboratory and field testing of commercial rotational seismometers. Bull Seismol Soc Am 99:1215–1227 CrossRef
Peterson J (1993) Observations and modeling of seismic background noise. U. S. Geol. Survey Open-File Report 93–322, 95 pp
Preumont A (2006) Mechatronics, dynamics of electromechanical and piezoelectric systems. Springer, Dordrecht, 207 pp
Riedesel M, Moore RD, Orcutt JA (1990) Limits of sensitivity of inertial seismometers with velocity transducers and electronic amplifiers. Bull Seismol Soc Am 80:1725–1752
Rodgers PW (1992a) Frequency limits for seismometers as determined from signal-to-noise ratios. Part 2. Feedback seismometers. Bull Seismol Soc Am 82:1071–1098
Rodgers PW (1992b) Frequency limits for seismometers as determined from signal-to-noise ratios. Part 1. The electromagnetic seismometer. Bull Seismol Soc Am 82:1071–1098
Scherbaum F (2001) Of poles and zeros, fundamentals of digital seismology, 2nd edn. Kluwer Academic Publishers, Dordrecht CrossRef
Scherbaum F (2007) Of poles and zeros, fundamentals of digital seismology, revised second edn. Springer, Dordrecht, 271 pp
Steim JM, Wielandt E (1985) Report on the very broad band seismograph. Harvard University, Cambridge, MA. 34 pp
Urhammer RA, Collins ER (1990) Synthesis of Wood-Anderson seismograms from broadband digital records. Bull Seismol Soc Am 80:702–716
Usher MJ, Buckner IW, Burch RF (1977) A miniature wideband horizontal-component feedback seismometer. J Phys E Sci Instrum 10:1253–1260 CrossRef
Usher MJ, Burch RF, Guralp C (1979) Wide-band feedback seismometers. Phys Earth Planet Inter 18:38–50 CrossRef
Wielandt E (2011) Seismic sensors and their calibration. In: Bormann P (ed) (2012) New manual of seismological observatory practice (NMSOP-2), IASPEI, GFZ German Research Centre for Geosciences, Potsdam; hnmsop.gfz-potsdam.de; doi: 10.2312/GFZ.NMSOP-2_ch5
Wielandt E, Streckeisen G (1982) The leaf-spring seismometer: design and performance. Bull Seismol Soc Am 72:2349–2367
- Seismic Sensors
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