{"id":14769,"date":"2011-03-26T17:47:50","date_gmt":"2011-03-26T21:47:50","guid":{"rendered":"https:\/\/www.windturbinesyndrome.com\/static\/static\/?p=14769"},"modified":"2012-01-21T12:37:32","modified_gmt":"2012-01-21T17:37:32","slug":"seismologists-say-wind-turbines-produce-airborne-infrasound-plus-ground-borne-vibration-up-to-6-8-miles-from-the-wind-farm-italy","status":"publish","type":"post","link":"https:\/\/www.windturbinesyndrome.com\/static\/2011\/seismologists-say-wind-turbines-produce-airborne-infrasound-plus-ground-borne-vibration-up-to-6-8-miles-from-the-wind-farm-italy\/","title":{"rendered":"Seismologists say wind turbines produce airborne infrasound plus ground-borne vibration “up to 6.8 miles from the wind farm” (Italy)"},"content":{"rendered":"

\u2014<\/span>Calvin Luther Martin, PhD<\/span><\/a><\/p>\n

A new study by a team of earthquake scientists (seismologists) in Italy has made a signal contribution to our understanding of wind turbine noise & vibration and, by extension, Wind Turbine Syndrome (WTS).<\/span><\/p>\n

Before examining their research, however, we need to put it in context—the context of Wind Turbine Syndrome (WTS) and the central role played by the utricle and saccule in triggering WTS.<\/span><\/p>\n

Those of you who’ve read Pierpont’s book, “Wind Turbine Syndrome,” are already familiar with the “vestibular organ story”: \u00a0that the\u00a0utricle and saccule (vestibular organs in the inner ear) evolved over millions of years to detect ground-borne (substrate-borne) low frequency\u00a0vibration. \u00a0The eyes\u2014to see<\/em>. \u00a0The nose\u2014to smell<\/em>. \u00a0And the ear\u2014to hear<\/em> (via the cochlea) and detect low frequency vibration<\/em> (via vestibular organs). \u00a0Indeed, as you learned from her book, the utricle and saccule are the low frequency vibration detectors for a host of creatures, in fish all the way up through mammalians—including yours truly.<\/span><\/p>\n

\"\"<\/a><\/span><\/p>\n

Secondly, we already know from human experimentation (<\/span>Todd et al. 2009<\/span><\/a>) that the utricle or saccule of the human is 15dB more sensitive to 100 Hz substrate-borne vibration than the cochlea.\u00a0\u00a0In other words, when incoming noise is so quiet you can’t hear it, the\u00a0utricle\u00a0and saccule still pick it up. \u00a0Such is their phenomenal sensitivity! \u00a0Moreover, we know there is\u00a0definitely\u00a0an infrasonic (low frequency) range of\u00a0sensitivity<\/em> in the utricle and saccule, although, at this point, it’s unclear what exactly the range of these frequencies is.<\/span><\/p>\n

In other words, the amount of vibration\/bone-conducted sound\u00a0was so small that the subjects could not hear it, yet the vestibular\u00a0parts of their inner ears still responded to the vibration and transmitted signals into the balance and motion networks in the\u00a0brain, resulting in specific types of eye muscle activation (eye muscle activation is a well-known marker for vestibular stimulation).<\/span><\/p>\n

Since\u00a0dB is a base 10 logarithmic measure, 15 dB below<\/em> means a signal\u00a00.0316 (10\u20131.5<\/sup>), or about 3%, of the power or amplitude of the signal\u00a0these normal subjects could hear” (Pierpont, Wind Turbine Syndrome<\/em>, pp. 86-87<\/a>).”<\/span><\/p><\/blockquote>\n

(Thanks to Dr. Alec Salt’s<\/a> research, scientists now know that the cochlea suppresses the hearing detection of low frequency noise. \u00a0Notice, this does not mean the low frequency noise has no effect on the brain; it merely means our ability to hear <\/em>it is suppressed, a fact the wind developers and their acoustician consultants don’t seem to grasp—or want to grasp?)<\/span><\/p>\n

With this as background, consider the following:<\/span><\/span><\/p>\n

\"\"<\/a><\/span><\/span><\/p>\n

VIRGO Gravitational Wave Observatory<\/a>, Italy<\/span><\/span><\/h6>\n

“Seismic Noise by Wind Farms<\/span>: A case study from the Virgo Gravitational Wave Observatory, Italy\u201d<\/a><\/h4>\n
\u2014by Gilberto\u00a0Saccorotti,\u00a0Davide\u00a0Piccinini,\u00a0L\u00e9na\u00a0Cauchie, Irene\u00a0Fiori<\/span><\/h6>\n

Abstract<\/span><\/h4>\n

We present analyses of the noise wave field in the vicinity of Virgo<\/a>, the Italian\u2013French gravitational wave observatory<\/a> located close to Pisa, Italy, with special reference to the vibrations induced by a nearby wind farm<\/span>. The spectral contribution of the wind turbines is investigated using (1) onsite measurements, (2) correlation of spectral amplitudes with wind speed, (3) directional properties determined via multichannel measurements, and (4) attenuation of signal amplitude with distance.<\/p>\n

Among the different spectral peaks thus discriminated, the one at frequency 1.7 Hz is associated with the greatest power, and under particular conditions it can be observed at distances as large as 11 km [6.8 mi] from the wind farm. <\/span><\/p>\n

The spatial decay of amplitudes exhibits a complicated pattern which we interpret in terms of the combination of direct surface waves and body waves refracted at a deep (\u2248800m = half a mile) interface between the Plio-Pleistocenic marine, fluvial, and lacustrine sediments and the Miocene carbonate basement<\/span>.<\/p>\n

We develop a model for wave attenuation that allows determining the amplitude of the radiation from individual turbines, which is estimated on the order of 300-400 \u00b5ms-1<\/sup>\/\u221aHz<\/em> for wind speeds over the 8\u201314 m\/s range.<\/p>\n

On the basis of this model, we then develop a predictive relationship for assessing the possible impact of future wind farm projects.”<\/p><\/blockquote>\n

\u00b7<\/span><\/span> <\/span>
\n<\/span>The following are key points from the paper. (Text in grayscale was inserted by CLM to clarify the translator’s imperfect English. \u00a0Sometimes the grayscale text is meant as a substitute for the confusing original text, as in the first line, below; other times it is an elaboration on the original text.)<\/span><\/span><\/h4>\n

Wind turbines are large and vibrating cylindrical towers strongly coupled\u00a0to the ground through a <\/span>massive concrete foundation, with rotating turbine\u00a0blades generating low-frequency acoustic signals noise<\/span>.<\/p>\n

The <\/span>Vibrations depict show<\/span> a complex spectrum, which includes both time-varying\u00a0frequency peaks directly related to the blade-passing frequency, and stationary peaks associated with the pendulum modes of the heavy rotor head and\u00a0tower, and to flexural as in flexing <\/span>modes of the tower.<\/p>\n

These disturbances noise\/vibrations <\/span>propagate via complex paths including directly through\u00a0the ground or though <\/span>principally through the air and then coupling diving <\/span>locally into the\u00a0ground.\u00a0<\/p>\n

Though weak, such vibrations may be relevant once compared to the\u00a0local levels of seismic noise. Schofield (2001) found that the intense low frequency seismic disturbances from the Stateline Wind Project (Washington-Oregon, USA) were well above the local seismic background till up to <\/span>distances of\u00a018 km from the turbines. Similar distance ranges were found by Styles\u00a0et al. (2005), who analysed the possible influence of a project wind park at\u00a0Eskdalemuir (Scotland) in the vicinity of the UK Seismic Array. Fiori et\u00a0al. (2009) studied the seismic noise generated by a wind park in proximity\u00a0of to <\/span>the GEO-600 interferometric antenna (Germany), and observed the signal\u00a0from the turbines till at <\/span>distances of about 2000m (2km = 1.24 mi)<\/span>.<\/p>\n

In this work, we present the results from 81 seismic noise analyses in the\u00a0vicinity of VIRGO, with special reference to the action of the wind park. \u00a0The paper is structured into four parts.<\/p>\n

In the first part (Sections 2-3), we\u00a0describe the geological setting of the study area and describe the data acquisition procedures. We then describe (Section 4) the spectral characteristics\u00a0of the noise wavefield, and their relationships with human activities human-generated noise <\/span>and the\u00a0wind field.<\/p>\n

In the third part (Sections 5 and 6), we use small- and large-aperture array deployments to investigate the directional properties of the\u00a0noise wavefield and its amplitude decay with distance from the windfarm.<\/p>\n

In the last part (Section 7) we propose an attenuation model involving the\u00a0combination of direct cylindrical waves propagating at the surface, and body\u00a0waves refracted at a deep (800m half a mile<\/span>) lithological rock<\/span> interface. This attenuation\u00a0law is eventually used for establishing a predictive relationship for assessing the range of seismic amplitudes which are expected in association with\u00a0narrow-band, shallow sources of noise.<\/p>\n

…………….<\/p>\n

Several out<\/del> <\/span>of the frequency peaks, which correlate well with wind speed\u00a0(e.g., 1.7, 3.5, 4.5 Hz on the NS component), attenuate as one goes farther\u00a0from the wind park, thus reinforcing the hypothesis that these peaks are due\u00a0to the action of the turbines. In particular, the peak at frequency 1.7 Hz is\u00a0clearly observed also at VIRGO\u2019s WE, about 11km 6.8mi <\/span>from the wind <\/span>energy plant.<\/p>\n

For this particular frequency, the decay of spectral amplitude with increasing distance from the source exhibits a complicated pattern (Fig. 8b). \u00a0In particular, we observe a marked change in the amplitude decay rate for\u00a0source-to-receiver distances on the order of 2500-3000m 1.6mi-1.9mi<\/span>.<\/p>\n

A simplified propagation model explaining the two different attenuation\u00a0rates involves the combination of direct surface waves and plus <\/span>body waves propagating along deeper paths, characterised by higher velocities and quality\u00a0factors.<\/p>\n

…………….<\/p>\n

In this paper we analysed the seismic noise wavefield in the vicinity of the\u00a0VIRGO gravitational wave observatory (Cascina, Pisa—Italy), with special\u00a0reference to the action of a nearby wind park composed by four, 2 MW\u00a0turbines.<\/p>\n

Using stations deployed at distances ranging between \u0019 1200m\u00a0and \u0019 11,000m 6.8mi <\/span>from the barycenter center <\/span>of the wind park, we obtained recordings of the noise wavefield over a wide range of site conditions and epicentral\u00a0ranges.<\/p>\n

We noted that path effects modify significantly the source spectrum,\u00a0implying that beneath-turbine measurements measurements taken directly beneath the turbine blades <\/span>are not fully indicative of the\u00a0effective contribution of the wind park to the far\u2013field ground vibration spectra.<\/p>\n

Therefore, the spectral components of the noise wavefield likely due to\u00a0the action of the wind park had to be discriminated calculated<\/span> on the basis of indirect\u00a0evidence, including: (i) correlation of narrow-band noise amplitude with\u00a0wind speed, (ii) directional properties, and (iii) attenuation with increasing\u00a0distance from the wind park.<\/p>\n

Basing Based <\/span>on these results, we individuated distinguished <\/span>several frequency bands likely due\u00a0to the action of the wind park. Among these, the most energetic is that at a <\/span>frequency of<\/span> 1.7 Hz which, under particular conditions (i.e., low cultural noise man-made noise <\/span>and strong wind) can be clearly observed at epicentral distances from the turbine array <\/span>as large as\u00a011km 6.8mi<\/span>.<\/p>\n

At this particular frequency, the <\/span>waves depict demonstrate<\/span> a complicated pattern of attenuation with distance, characterised by a marked decrease in the decay rate for\u00a0ranges larger than 2500\u20133000m 1.6-1.9mi<\/span>.<\/p>\n

We interpreted this pattern in terms of a simplified propagation model involving the combination of direct, cylindrical waves and body head waves\u00a0continuosly refracted at a deep (\u0019800 m half a mile<\/span>) interface separating the shallow\u00a0marine-lacustrine lake<\/span> sediments from the carbonate basement. This model is\u00a0based on several simplifying assumptions, including: (i) seismic energy is\u00a0equally parted divided <\/span>into surface and head body waves, and no other wave types\u00a0and\/or wave conversions are allowed, and (ii) site effects are negligible.<\/p>\n

By further assuming that (i) each turbine radiates the same amount\u00a0of energy; (ii) signals from individual turbines sum add <\/span>constructively, (iii) the\u00a0velocity structure of the propagation medium is laterally homogeneous, and\u00a0(iv) local amplification effects are negligible, we thus defined a model relating\u00a0the seismic amplitude recorded at a given distance to the radiation of each\u00a0individual turbine.<\/p>\n

………………<\/p>\n

Gilberto Saccorotti and Davide Piccinini are both at the\u00a0Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Pisa Via U, della Faggiola, 32-56126, Pisa, Italy. <\/span>saccorotti@pi.ingv.it<\/span><\/a> and <\/span>davide.piccinini@ingv.it<\/span><\/a><\/p>\n

L\u00e9na Cauchie is at the\u00a0UCD School of Geological Sciences, University College Dublin, Belfield, Dublin 4, Ireland. <\/span>lena.cauchie@gmail.com<\/span><\/a>. \u00a0Also at Istituto Nazionale di Geofisica e Vulcanologia, Pisa, Italy.<\/span><\/p>\n

Irene Fiori is at the\u00a0European Gravitational Observatory, Via E. Amaldi 56021, S.Stefano a Macerata, Cascina (PI), Italy. <\/span>irene.fiori@ego-gw.it<\/span><\/a><\/p>\n

\u00b7<\/span>
\n<\/em>Click here<\/a> for the full article, Bulletin of the Seismological Society of America, <\/em>April 2011, v. 101, no. 2, p. 568-578.<\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"

\u2014Calvin Luther Martin, PhD A new study by a team of earthquake scientists (seismologists) in Italy has made a signal contribution to our understanding of wind turbine noise & vibration and, by extension, Wind Turbine Syndrome (WTS). Before examining their research, however, we need to put it in context—the context of Wind Turbine Syndrome (WTS) and the central role played by the utricle and saccule in triggering WTS. Those of you who’ve read Pierpont’s book, “Wind Turbine Syndrome,” are already familiar with the “vestibular organ story”: \u00a0that the\u00a0utricle and saccule (vestibular organs in the inner ear) evolved over millions of years to detect ground-borne (substrate-borne) low frequency\u00a0vibration. \u00a0The eyes\u2014to see. \u00a0The nose\u2014to smell. \u00a0And the ear\u2014to hear (via the cochlea) and detect low frequency vibration (via vestibular organs). \u00a0Indeed, as you learned from her book, the utricle and saccule are the low frequency vibration detectors for a host of creatures, in fish all the way up through mammalians—including yours truly. Secondly, we already know from human experimentation (Todd et al. 2009) that the utricle or saccule of the human is 15dB more sensitive to 100 Hz substrate-borne vibration than the cochlea.\u00a0\u00a0In other words, when incoming noise is so quiet you can’t hear it, the\u00a0utricle\u00a0and saccule still pick it up. \u00a0Such is their phenomenal sensitivity! \u00a0Moreover, we know there is\u00a0definitely\u00a0an infrasonic (low frequency) range of\u00a0sensitivity in the utricle and saccule, although, at this point, it’s unclear what exactly the range of these frequencies is. In other words, the amount of vibration\/bone-conducted sound\u00a0was so small that the subjects could not hear it, yet the vestibular\u00a0parts of their inner ears still responded to the vibration and transmitted signals into the balance and motion networks in the\u00a0brain, resulting in specific types of eye muscle activation (eye muscle activation is a well-known marker for vestibularRead More…<\/a><\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[163,16],"tags":[],"_links":{"self":[{"href":"https:\/\/www.windturbinesyndrome.com\/static\/wp-json\/wp\/v2\/posts\/14769"}],"collection":[{"href":"https:\/\/www.windturbinesyndrome.com\/static\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.windturbinesyndrome.com\/static\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.windturbinesyndrome.com\/static\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.windturbinesyndrome.com\/static\/wp-json\/wp\/v2\/comments?post=14769"}],"version-history":[{"count":0,"href":"https:\/\/www.windturbinesyndrome.com\/static\/wp-json\/wp\/v2\/posts\/14769\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.windturbinesyndrome.com\/static\/wp-json\/wp\/v2\/media?parent=14769"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.windturbinesyndrome.com\/static\/wp-json\/wp\/v2\/categories?post=14769"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.windturbinesyndrome.com\/static\/wp-json\/wp\/v2\/tags?post=14769"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}

\u00b7<\/span>
\nBy In<\/span> mid 2008, a wind park composed by of <\/span>four, 2MW turbines was installed at\u00a0some 6km east of VIRGO\u2019s NE<\/a>. After then subsequently<\/span>, plans were submitted\u00a0to local authorities for (i) adding three additional turbines to the existing\u00a0wind park, and (ii) installing a new, 7-turbine wind park at a site located\u00a0about 5km west of VIRGO\u2019s WE. As a consequence, EGO (the European Gravitational Observatory) asked the Italian Istituto Nazionale di Geofisica e Vulcanologia (INGV hereinafter) to\u00a0conduct a noise study aiming aimed <\/span>at (i) verifying properties and intensity of the\u00a0vibrations produced by the present aerogenerators wind turbines<\/span>, with the ultimate goal of\u00a0(ii) assessing the possible impact of the project wind parks.<\/p>\n