Rumbles and Mistpoeffers in Val PELLICE (Western Piedmont
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GNGTS 2014 SESSIONE 2.1 RUMBLES AND MISTPOEFFERS IN VAL PELLICE (WESTERN PIEDMONT) WITH AND WITHOUT EARTHQUAKES: A COMPARISON BETWEEN RADON 222 AND INFRASOUNDS MONITORING AND UNUSUAL ANIMAL BEHAVIORS G. de Liso1,2,3, A. Viotto1 1 Seismic Precursors Study Center (SPSC), Torre Pellice (TO), Italy 2 Istituto di Alta formazione artistica e musicale G.F. Ghedini, Cuneo, Italy 3 Voce Pinerolese, Pinerolo (TO), Italy Historical accounts and local people witnesses: a perceptive description of rumbles. The area of Val Pellice, located in western Piedmont, has a moderate seismicity, the recent classification of the seismic risk is 3S, but sometimes it is the theatre of earthquakes with magnitudes greater than 4 and 5 Richter, like the famous seismic event of April 2, 1808, with a magnitude recently estimated in 5.7 Richter. Regarding this latter earthquake, we have in Pinerolo an interesting relation of physicist G. Eandi and of captain L. Garola: they reported several observations during the long period of the following seismic storm, recording monitoring of chemical and physical parameters, unusual animal behaviors, anomalous atmospheric phenomena and seismic rumbles. Recently, the first author has added to monitoring of a few physical parameters also a research about local people witnesses of pre-seismic and seismic observations. It is very interesting to note that people living near the top of Vandalino Mountain or near Castelluzzo Peak, are better qualified to observe nature than people living in the centre of villages in Val Pellice: so during a seismic period, more observations by farmers are possible about anomalous animal behaviors and rumble or mistpoeffers. A statistic research on this topic is going on, but it is necessary to consider a more consistence of anthropic influences in centre of villages or little tows and different geologic morphology of areas of Castelluzzo-Bonnet, Vandalino’s top, outer hamlets of Angrogna, Villar Pellice, Bobbio Pellice and Rorà. The no-profit association Seismic Precursors Study Center (SPSC), which collects these data, is located in Torre Pellice (44°49’235” N, 7°123’04” E, western Piedmont, NW Italy) at 699 m above sea level on Vandalino Mountain, not too far an abandoned iron mine, near a particular “geological sanctuary” (Compagnoni and Sandrone, 1981) of Castelluzzo. The area of Castelluzzo and Bonnet is rich in augen-gneiss, of eruptive origin, in biotite, ophiolite, zeolite, pechblenda and in “Luserna Stone” (gneiss). Around Castelluzzo Peak it is possible to observe a slight geothermal activity, with warm emission of sulphureous gases from rock cracks. It is also interesting to note in the local toponymy a few names that have evident connection with the presence of creeks with moderately warm water (Rive chaud, La Chauda…). This is also present in areas of Barge (Cuneo), near Bracco Mountain and near Rocca of Cavour. Both mountains have characteristics similar to those of Vandalino Mountain. In Val Pellice it is possible to hear frequently rumbles, and it is necessary to do an accurate description of them, on the basis of perceptive acquisition of their origin, direction and temporal term. Often these rumbles follow the rapid rise of grey-ochre clouds from ground depressions at the top of Vandalino, or near Castelluzzo, or near the Bric Bucie (Bobbio Pellice). The rumbles can be perceived as underground or air rumbles: a)- underground rumbles can be perceived as long underground thunders, as underground rolls of timbals or of kettle drums (not of drums without resonance case), as an underground landslide of big rolling stones, as underground “mistpoeffers” similar to far gun shots, but acoustically stifled, “brontides”, similar to the closing of a big underground door; b)- rumbles in air can sometimes perceived as single blows in air, without echo, or wind blows, with a temporal long term, or as far gun shots in air, with a long period of detonation. Taking into consideration the historical accounts of Eandi, it is important to underline that the observations of Eandi and Garola are similar to those reported by the first Author, in the same region, in Val Germanasca and Val Chisone. ���������������������������������������������Moreover, there is an interesting citation in poetic verses of lyric aria “La calunnia è un venticello”, written by the composer Gioacchino 21 001-502 volume 2 21 5-11-2014 16:51:01 GNGTS 2014 SESSIONE 2.1 Rossini, contemporaneous of Eandi, that says: “La calunnia è un venticello, un’auretta assai gentile… un tremuoto, un temporale… che fa l’aria rimbombar, come un colpo di cannone…”. Rossini was impressed by the chronicles of earthquakes in Val Pellice and the same words of Eandi are present in the lyric aria in “Barbiere di Siviglia”, whose librettist is Cesare Sterbini, that compares the progressive diffusion of slander to a seismic phenomena. In lyric literature this comparison slander-seismic phenomena-volcanic explosion is often present, according to a popular knowledge concerning seismic and pre-seismic phenomena. With reference to rumbles similar to underground rolls of timbals, we must observe another comparison with musical language: these rumbles have a progressive rise in frequencies and intensity, as in a “Beethoven’s crescendo and diminuendo” or as in a “crescendo rossiniano”, we can better observe this characteristic in images of infrasound monitoring, thanks to Spectrum Lab elaborations. Often, in these cases there are contemporaneous earthquakes. Generally, in the case of underground rumbles, there is a contemporaneous little local trembling of the ground, not necessary an earthquake, that often happens 8-15, sometimes 20 hours before earthquakes with epicenter 50-150 km far from Torre Pellice, generally in the area of Cuneo, of Barcelonette or of Brianḉon (France); if there is an important, long storm of shots and rumbles. So we can consider this local trembling following underground rumbles on Vandalino as a phenomenon connected to another future seism with a farther epicentre. In a few cases, rumbles similar to gun shots (observed in Torre Pellice and in a big area of Piedmont and Liguria) happened after earthquakes with magnitude of 4.6 Richter (July 2011), and after a 5.0 Richter (April 2014) in the French Southern Alps, but one time the same rumble happened in Val Pellice 40 minutes before a seism with a magnitude of 0.8 Richter, near Acceglio (July 2012). Sometimes, rumbles and “mistpoeffers” are localized very well in Castelluzzo Peak, in a small underground area of 500-700 m of height: below this area you can hear the rumble above it, while above this area the rumbles can be heard from below. People living near Castelluzzo have the same perception. Often, rumbles, localized in Rorà’s area or in the nearby Frioland Mountain, are followed by a local seism after 50-80 minutes, if there is a sequence of rumbles after the first one. In the consideration of eventual connections between rumbles as pre-seismic or post-seismic phenomena and earthquakes, it is important to take into account the difference of geological micro-zones. Then, it is necessary to distinguish rumbles and brontides where no earthquake follows from the rumble of a seism taking place. In the area of Rorà and Barge there are several gneiss mines, so it is important to differentiate natural rumbles from mine detonations: explosion rumbles of mines have higher frequencies than natural rumbles, they are very short and animals (generally dogs and birds) always cry after these detonations. In the case of natural rumbles and “brontides”, animals cry 70-80 seconds before them, but a wider number of animal species is interested, crying together: dogs, donkeys, cows, cocks, chickens, crows, buzzards, night-birds of prey. Concerning night-birds of prey, they usually scream during the night, but in the case of brontides they cry also during the morning or the afternoon. A musical sensibility in acoustic perception can assist while considering little differences in the tonal language of animals during their normal life or during situations of alarm. In case of rumbles and brontides followed by earthquakes, vocal animal alarms are like those observed in phase C, before earthquakes (de Liso and Fidani, 2014; de Liso et al., 2014); vocalizations are more excited and, bearing in mind dog cries, we can hear melodic dissonant intervals. In case of rumbles and brontides without subsequent earthquakes, the shrills are less frequent, but always excited (generally high and with melodic dissonant intervals) and the temporal period of vocal alarm is shorter than in phase A (several hours before earthquakes). Infrasound monitoring: instrumentation, monitoring modality, Spectrum Lab’s images of rumbles. Instrumentation. In SPSC an infrasound monitoring by an Infrasound Aetech Meter 22 001-502 volume 2 22 5-11-2014 16:51:01 GNGTS 2014 SESSIONE 2.1 has been active for two years, with the following characteristics: Power voltage: Battery 12 volt Dimensions: 300x210x35mm, 1 kg. Degree of protection: IP 44 USB range of measures: 0-20 Hz. VCO range of measures: 0-35 Hz. Stabilization time: 40-50 S. Graphic display: USB interface Acoustic gauge: B.F. exit:1175 - 2400 Hz. Central frequency: 1780 Hz. Battery life: 6 hours Sensor: Infrasounds pickup of Aetech Infrasounds Monitor The Infrasound Meter is placed in SPSC basement of the first author’s house, as we can see in Fig.1. The sensor of the infrasound detector is placed near a wall, at a distance 15 cm from it (de Liso et al., 2013). Fig. 1 – Location of the infrasound Meter. Monitoring methodologies. The monitoring, continuous and connected with a computer, is intentionally placed to this day in the first author’s house, near a forest, in an area with little anthropic disturbance. Normal family life gives the first author the possibility of discrimination between anthropic and natural sounds, rumbles and so on, thanks to images formed by the Spectrum Lab.