The high resolution scan laboratory (HRSL) aims to acquire high resolution images of historical seismograms in raster format. With the advent of digital acquisition systems of seismic data the data analysis techniques have radically changed, allowing us to analyse, with numeric methods, the wave forms and to elaborate mathematical-physical models capable of effectively describing the dynamics of the earth’s crust. The SISMOS project allows us to produce, conserve and disseminate the data in digital format not subject to deterioration and subsequently to analyze them with modern techniques.
High resolution scan
The operations in the HRSL follow the meticulous work of historical research and cataloguing of the seismograms. The main information on the seismogram are summarised in a bar code.
After a painstaking association between the seismogram data, memorised in the database during the cataloguing phase, and the seismogram itself, we proceed with the scan with two high resolution scanners (Eskoscan 2636 with resolution up to 2500 dpi) which in this specific instance operate at 1016 dpi.
The resulting raster data are archived on hard disks and are subsequently stored in two copies, including a DVD-ROM. For data safety, each copy of the DVD is archived in different INGV sites.
The acquisition resolution has been established so as to guarantee that there is no loss of information in the passage from the analogical recording to the raster image. Indeed, on the grounds of the period itself of the instrument, it is guaranteed that the minimum significant frequencies resolved by the instrument, will be sampled during the acquisition phase with a sufficiently high number of pixels.
The reproduction plane for each scanner is 118 cm x 90 cm and this generally allows for same-session scanning of 3 seismograms 90 cm long and 30 cm wide or 2 seismograms of between 30 cm and 50 cm in width. Instead, for seismograms longer than 90 cm reproductions are made in pieces. An integral reproduction session involves a scan time varying between 20 and 30 minutes and involves between 2 and 3 seismograms, depending on their width.
The system is able to scan seismograms on smoked, photographic, thermal paper or by means of ink recordings.
Subsequently, quality control is performed, an important operation for guaranteeing the correct alignment of the seismogram in the rectangle of reproduction and a correct transfer into the main storage of the rasters produced.
At the end of the scan of a set of seismograms the SISMOS database procedure is started, which allows for a further and definitive control of the data (association between Label – Seismogram and JPG File. This final procedure allows the person in charge of the room to upload, by means of a Web page, the definitive data in order to start up the back-up procedure.
At present, SISMOS has achieved a productive capacity of around 16,000 seismograms scanned per year. With the same technologies and technical staff, by improving the organisation, it is thought that the target of 20,000 scans per year can soon be achieved. The graph reported summarises the weekly production of the SISMOS HRSL and the progressive cumulative data.
The high costs of the mass storage memories and organisational issues have hitherto prevented the online upload of all the high resolution images at the same time (over 140,000 of them today). Soon a 50TB mass storage memory will be implemented which will allow for the upload of all the seismograms hitherto scanned and to have at least another year’s autonomy with the new storage capacity.
Alessio Mautone (Person in charge from 2008)