The seismological correspondence at the Observatory of the Alberoni College in Piacenza

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ANNALS OF GEOPHYSICS, VOL. 52, N. 6, December 2009

Key words history of seismology – Alberoni Obser-vatory – seismic instruments

1. Introduction

The Alberoni College in Piacenza have along and important tradition of research in thefield of Earth Sciences. An astronomical Obser-vatory was founded at the College in 1751 fol-lowing the initiative of Cardinal Giulio Alberoni(1664-1752). In 1802, regular meteorologicalobservations started at the Observatory. At themoment the first measures have not been found,we have only the register from 1805 to 1809 –preserved at the Palatina Library of Parma andfrom 1833 to 1868 at the Alberoni College.

Seismological observations started in 1861but in the historical registers of the Meteorolo-

gical Observatory, working since 1802, inher-ent traces of the first seismic data were found.The promoter was Father G.B. Manzi, scienceteacher and Director of the Meteorological Ob-servatory (fig. 1). In 1870 G.B. Manzi revivedmeteorological observation on new bases andhad a meteorological tower built with adjacentdome for the astronomical observations. Be-sides making stable and continuous the meteor-ological reliefs, Manzi contributed, experimen-tally, to carry out observations with a Cavalleripendulum seismograph. The parametric figuresrelated to the rudimentary seismic instrumentwere never included in the registers and thespaces reserved to it were eliminated after a fewmonths. Activity was developed, like the mete-orological one, in the rooms at the second floor,where there is still the classroom of physics.

In 1874 Manzi bought a Bertelli one com-mon prism tromometer, and then one Galli typeseismoscope, one Galli Brassart seismic warn-ing device (fig. 2) and one Agamennone seis-moscope. Regular tromometric and geomagnet-ic observations were carried out from 1883 to1915 (fig. 3).

The seismological correspondence at the Observatory of the

Alberoni College in Piacenza

Matteo Cerini (1) and Graziano Ferrari (2)(1) Osservatorio Geofisico Alberoni, Piacenza, Italy

(2) Istituto Nazionale di Geofisica e Vulcanologia, Bologna, Italy

AbstractThe Observatory of Collegio Alberoni in Piacenza boasts a long tradition of observations in the field of the EarthSciences. Founded first of all as an astronomical observatory in 1751 it gradually specialized also in meteoro-logical observation starting in 1802 and that of instrumental seismology starting in 1861. The instrumental ob-servation of earthquakes in the modern sense started in the 1920s and is documented by an epistolary archiveof some 200 letters (1913-1972) described here in brief. The Observatory has a broad-ranging initiative ongoingfor the recovery of the historical scientific wealth of its long tradition in which the letters themselves play a veryimportant role.

Mailing address: Dr. Matteo Cerini, OsservatorioGeofisico Alberoni, Via Emilia Parmense, 29100 Piacenza,Italy: e-mail: [email protected]

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M. Cerini and G. Ferrari

Fig. 1. The Alberoni Observatory in a photograph of the end of 19th century (Archive of the Ufficio Centraledi Ecologia Agraria, Rome).

Fig. 2. Galli-Brassart seismic worning device.

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The seismological correspondence at the Observatory of the Alberoni College in Piacenza

The first and significant collaborations weremade with the Moncalieri Observatory (close toTurin) and the seismic observations were regu-larly sent to the Ufficio Centrale di Meteorolo-gia e Geodinamica (UCMG - Central Office ofMeteorology and Geodynamics) of Rome.

We have meager pieces of information onthe relationship between Manzi and the expo-nents of the Italian scientific community. We al-so have not much news on the management ofthe scientific section of the Alberoni College. Inthe archives of the Institute, there is only oneinvoice related to the purchasing of meteorolog-ical instrumentation.

Up to here the story has been told by vari-ous published, or unpublished and fragmentarytestimonies. In the 1920s the history of themodern seismological Observatory started,largely documented by the correspondencearchive of the Observatory itself. From lettersdated 1919-1920, we have the first indicationabout the interest of Pietro Andreoli, who suc-ceeded Manzi in 1914, to buy more suitable andmodern instrumentation for the seismic section

of the observatory, which still did not have seis-mographs for continuous recording.

2. The archive of scientific correspondence in the recent history of the Alberoni Observatory

The archive is made up just over 200 lettersreceived between 1913 and 1972, above all of aseismological nature. More correspondencemakes up the contemporary collection. Themost assiduous correspondent was GiovanniAgamennone with 48 letters between 1913 and1939, many of which dedicated to the horizon-tal seismograph designed by the scholar and al-so installed at the Observatory. Another assidu-ous letter-writer was Pietro Caloi with 20 lettersbetween 1932 and 1948. The graph of fig. 4shows the number of letters for the five-year pe-riod contained in the Observatory’s epistolarycollection. The letters were catalogued andscanned in the early 1990s within the scope ofthe Tromos Project (INGV-SGA, 1990-2007).

Fig. 3. Tromometric and geomagnetic observations from the register preserved at the Alberoni Observatory.

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Relations with the main designers of Italian andforeign seismic instruments are documented bynumerous letters: 6 letters of the instrumentsfactory Wiechert Bertels in 1923, 6 letters ofVicentini from 1924 to 1927, 1 of Conrad in1924 and 7 letters between 1922 and 1923 ofGiulio Grablovitz, director of the GeodynamicObservatory of Casamicciola (Isola d’Ischia –Southern Italy). The letters tell the story of howone of the best equipped observatories of itsday was born.

On 7th July 1921 one Agamennone hori-zontal pendula microseismograph built at theUCMG, was sent to Piacenza; it was placed ina room at the ground floor of the buildingwhere Manzi performed the geomagnetic andmicroseismic observations (fig. 5). Andreoli

pressed to the director of UCMG Luigi Palazzoto have a three component version of the Aga-mennone seismograph in order to complete theequipment, but the answer was negative, be-cause they could not make structural changes tothe instrument under construction.

In May 1922 a system for the reception ofthe chronometric signals, used for correctingthe system joined to the instrument, was lentfrom the maritime military arsenal of Spezia.

In the summer of 1922 Giovanni Agamen-none personally tested his microseismograph.However the first seismograms date back to1921, even though part of them were notsigned. The instrumental replacement allowedthe Observatory to be included in the nationalseismic bulletins.

Fig. 4. Number of letters for five-years period of the Alberoni Observatory epistolary from 1920 to 1950. Afterthis period few letters survived.

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In March 1923 the seismic Observatory wasequipped with one Wiechert astatic horizontalseismograph with a mass of 1000 Kg. The in-strument coming from the Hydrographic Ob-servatory of the Royal Navy of Pola, was as-signed (under agreement) to internal use in theInstitute, but even for providing data to externalresearchers. During the first phase of the com-plex negotiation, it seemed that the instrumentwould remain with a government and not a pri-vate facility. Andreoli took the transport uponhimself. The seismograph was in fairly good re-pair. The assembly and the testing of the deli-

cate and sophisticated seismograph were per-formed by the firm Bartels of Gottingen (fig. 6).There are few pieces of information related tothe Conrad horizontal pendulum seismograph,installed in 1924; it was rarely used.

One of the four rooms of the Observatory,was turned into an archive and to smoke paperfor mechanical recording. Some accessories forthe procedures of smoking were given up withthe Wiechert seismograph.

In November 1924 Andreoli got in touchwith Giuseppe Vicentini renowned seismologistand teacher of Physics at Padua University. Theseismic center of the Alberoni College needed avertical component instrument. The triaxialsystem (two horizontal seismographs and onevertical) would have been provided with mag-netic damping in comparison with the previousnot damped ones; so there would be increasesin periods of masses oscillation cutting downthe weight. The two horizontal componentswould have been separated from each other(fig. 7). The wait was rather long because of or-ganizational problems inherent in the construc-tion of the microseismograph. The instrumentwith vertical pendulum mass was fitted with amercury thermal compensator that made up forthe variations in temperature of the metallicarm. The job was commissioned from Ferro’sscientific shops of Turin. The microseismo-graph was installed in 1927.

Obviously the scientific equipment was puton columns and concrete separated from thestructure of the building, so that they could bet-ter transmit the seismic waves to the instru-ments. The planners of the construction of thebuilding supports were very shrewd.

From 1925 the direction of the Observatorywas managed by Mr. Zeppieri, the first authorof the scientific publications of the AlberoniCollege. In the 30’s, the instrumental collectionput the seismic Observatory among the mostequipped in Italy. From 1935 the empirical fig-ures related to the macroseismic local fields andto parametric instrumental ones were telegraph-ically transmitted to the Central Office of Mete-orology and Geophysics. The station bookswere drawn up with scientific rigor and includ-ed information on the damage caused by theearthquakes. There are several numerical and

Fig. 5. Card from Luigi Fascianelli, the official in-strument maker of the Central Office of Meteorologyand Geodynamics, to Andreoli, the director of theObservatory (September 2nd, 1920) in which asketch of the Agamennone seismograph with twohorizontal components is reported with the relatedmeasurements.

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graphic figures inherent in the instrumentalconstants. The recordings were partially pre-served up to 1927. From 1928 to 1943 therewas no discontinuity. From 1944 only the seis-mograms with seismic events were stored in thearchives. Altogether there are 17,305 historicalseismograms (15,325 from Wiechert astaticseismograph, 1,601 from Vicentini microseis-mograph, 375 from Agamennone seismographand 4 from Conrad).

In the sixties the activity of the Agamen-none seismograph was suspended, the Vicenti-ni in 1970 and the Wiechert in 1996. Father Ce-sare Pizzi, who succeeded Emidio Prata (direc-tor in the 40’s and 50’s), wanted further instru-mental updating. To better study the instrumen-tal and local macroseismic activity and to pro-vide more reliable data to the National Instituteof Geophysics, a seismometric triad with ana-logical writing apparatus and electronic ampli-fication was purchased. The data were nolonger furnished regularly to the Institute afterthe sixties. An agreement was signed in March1976. The earthquake locations were made by arudimentary computerized system of calcula-tion. In 1992 after the death of Cesare Pizzi, the

Observatory was inactive for about six months.Currently the Observatory has digital instru-

ments. The archive has been reorganized and itwas made a computerized cataloguing of allseismograms. Data related to the events havebeen included in a database. The historical in-strumentation was restored in 2008.

3. Conclusions

The long and important scientific traditionof the Observatory of the Collegio Alberoni isdocumented by manuscripts of meteorologicalrecordings from the start of the 19th centuryand seismic ones from the 1880s and a reduced,but important historic epistolary collectionfrom 1913 to 1972. The latter in particular doc-uments the phase of updating the seismic in-strumental equipment of the Observatory thatmade it one of the most modern of the day. TheObservatory has a far-reaching initiative ongo-ing for the recovery of the historical scientificassets of its long tradition. A complete cata-loguing has been undertaken of the over 17,305seismograms recorded from 1921 to 1996 with

Fig. 6. Letter of the Bertels farm concerning the installation of the Wiechert seismograph at the AlberoniObservatory.

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the mechanical recording instruments and thecataloguing and the digital reproduction of thewhole epistolary collection. Also being com-pleted is the restoration of all of the historicalinstrumentation. The Observatory, which pre-

serves its current activity of instrumental moni-toring, takes part in the initiative of the SIS-MOS project of virtual recomposing of the his-torical network of the scientific observation ofearthquakes in Italy.

Fig. 7. Vicentini Horizontal seismograph preserved and recently restored at the Alberoni observatory.

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The seismological correspondence at the Observatory of the Alberoni College in Piacenza