Historical Seismograms - Evidence from the AD 2000 Izu Islands ...

448 R. Console and P. Favali2. The Archives of the Rocca di Papa ObservatoryThe Royal Geodynamics Observatory of Rocca di Papa was installed in 1888by a governmental decree. It operated with a variety of seismographs, most ofthem designed by its director, Professor G. Agamennone. A new law transferredthe task of seismological observations from the Central Office of Meteorology andGeodynamics to the new Istituto Nazionale di Geofisica (ING) in 1936. All thehistorical records and the library, as well as the observatory building, became part ofING, and the old seismographs were replaced by relatively new equipment (Wiechertmechanical seismographs).Fortunately, Prof. Agamennone kept voluminous books (each of them coveringabout 1 year) that contained information about earthquakes. Essentially, they containedsystematic 'readings" of seismograms and periodically revised instrumentalparameters and the most significant records themselves. Because of this, the INGcan access a large set of historical seismograms and have a good idea of the kind ofinstruments that recorded them.Not all the volumes from 1888 to 1936 are available at present. Table 1 showsthe sequence of dates covered by the existing volumes.Table 1. Seismological Observations at Rocca di PapaVolume Dates (from) (to) Volume Dates (from) (to)IXIVI1 XV 23 Oct 1907 16 May 1908111 XVI 17 May 1908 22 Sep 1909IV XVII Oct 1909 Oct 1910V 17 Aug 1899 31 Dec 1900 XVIIIVI XIX 4 Jan 1912 30 May 1913VII 1 Sep 1901 31 Dec 1901 xx Jun 1913 Dec 1914VIII 1 Jan 1902 11 Jun 1902 XXI Jan 1915 Aug 1915IX 14 Jun 1902 31 Dec 1902 XXII Sep 1915 Jul 1916X 1 Jan 1903 31 Dec 1903 XXIIIXI 1 Jan 1904 31 Dec 1904 XXIVXI1 1 Jan 1905 6 Nov 1905 xxvXI11 XXVI Jan 1919 Dec 19203. Examples of Existing Historical Seismic RecordsFigures 1, 2 and 3 illustrate 3 strong Italian earthquakes recorded at the beginningof the century at Rocca di Papa. Table 2 gives the origin time, coordinates, depth,magnitude, maximum intensity, and epicentral distance of the 3 earthquakes.Table 3 gives the instrumental constants for the seismographs that provided therecords in Figures 1-3 and Table 2. Damping factors were not considered to be essentialat that time. These seismographs differed from the usual mechanical instrumentsrecording on smoked paper in that they remained on standby until triggeredby ground motion.