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

450 R. Console and P. FavaliTable 2. Some Examples of Earthquakes Recorded at Rocca di Papa (RDP)Date Time Inst. Epicenter h Ms I. A Locationyear mo da hr:mn:scLat . Long.1904 02 24 15:53:26 A 42'07' N 13'20' E 6 5.6 9 60 Marsica1908 12 28 04:20:27 A 38'10' N 15'35' E 10 6.9 11 470 Messina1915 01 13 06:52:43 B 41'59'N 13'36'E 8 6.6 11 60 AvezzsnoInstruments: A = Agamennone, B = Brassart.Table 3. Instrumental ConstantsSismometrografo UAgamennone" a doppia velocit&M = 200 kg, T = 4.4 sec, A = 14Sismometrografo uBrassart" a tre componenti con lastra di vetroM = 26.4 kg, T = 3.5 sec, A = 10The first instrument (designed by Agamennone) recorded two horizontal componentson a strip of white paper (sometimes blue and red ink were used for N-S andEW components, respectively). Usually the paper speed was about 5 mm/min,but when an external pendulum produced an electric contact, the speed increasedto about 5 mm/sec and the timemarks accelerated from 1 min to 1 sec. After 1minute, the paper driver returned to normal.The second seismograph (designed by Brassart) is actually a parent of our modernstrong-motion recorders. It recorded all three components on a plate of smokedglass,which moved at a speed of 6 mm/sec when an external seismoscope detecteda light movement and triggered the motor. The seismograms available in our fileare contact-print photocopies of the original smoked plates.4. Conclusions and Suggestions for Future WorkOur program for reevaluating the old records consists of the following steps: (1)Compilation of a catalog of existing records, including all available information oninstrumental parameters; (2) Study of the problem of obtaining magnitude valuesfrom maximum amplitudes and/or durations; (3) Digitization of seismogramsrecorded at a high rate of paper speed; and (4) Study of the problem of analyzingwaveforms to obtain ground displacement and spectra from seismograms.If adequate financial support and manpower are available, we intend to carry outthe above program not only for the Rocca di Papa Observatory, but possibly also forother old observatories on a national scale. Cooperation with international initiativeslike the International Historical Seismograms Filming Project is also planned.