Abstract

Within the scope of data acquisition and data manipulation from the different updated database relative to seismic risk evaluation in Italy, we collected and made available, in a consistency way, a lot of information in the SSN databank.
The data bank created, has been structured with more then 70 vector data bases and 10 raster data bases.

INTRODUCTION

In March 1996 the GIS office of the Italian Seismic Survey started a reconfiguration and transformation project of all seismic data of the National territory and their relative associated information, stored in the existing information system.
The development of the project and its further functional implementations, allows to accomplish the following goals:

• a better access to the information - a direct well organized structure of the metadata make easier researches and inquires;
• a better quality of the data - the data are subjected to a detailed verification of their accuracy, consistency, precision and relative documentation, before storing;
• a direct access of the users to the data trough a dedicated and friendly environment system for each kind of user;
• faster access to the data – data consistency and flexibility make them immediately available for further implementation or reports.

The project was born because the Italian Seismic Survey, wanted to be conformed to the A.I.P.A. (authority for IT in the Public Administration) directives based on the study of feasibility for the definition of a communication system of spatial data through the Public Administration Network.
This project will also represent the contribution that the Italian Seismic Survey will bring to the "GEOSERVER project" of the Italian Department for Technical Services.
The project has been divided in the following sub projects:

• metadata: design and development of metadata forms (at two difference levels of detail) and of their query system;
• databank: design and development of the databank including both cartographic and standard thematic data;
• data management system: manteinence and updating of spatial data, their attributed and associated information;
• communication system: access to spatial data and information from internal and external users.

Picture 1 shows the actual system architecture.
In the following paragraphs will be described the work and the results of the "databank subproject" which consists in a database collection of a remarkable size, representing an efficient working tool for everyone who wants to work in seismic field in Italy.

THE CARTOGRAPHIC DATABANK

With the "databank subproject" has been developed the cartographic databank dedicated to the study of seismic risk evaluation in Italy. The data come from the National Seismic Survey info system and they have been restructured to be effectively used in the normal information activities and in decision supporting system during the seismic event management in "Crisis Rooms".
The work for this subproject took two years, and it has been articulated in different steps that they can be briefly described hereafter:

1. census of the national vector and raster based cartography, or alpha-numeric data stored in the National seismic Survey info system;
2. acquisition, from others Public Administration Agencies, of other important data necessary for the accomplishment of our institutional duties;
3. definition of the data minimum requirements for the storage in the databank;
4. definition of a descriptive data-form both for vector data and raster data, and consecutive filling of the same form for those data which characteristics matched requirements illustrated at point 3;
5. design of the physical and logical structure;
6. data migration into the databank;
7. filling of metadata forms for each database implemented (general description of the database stored).

Among the database present in the Italian seismic national system, only those falling into the following requirements have been including in the databank:

• they must describe the whole National Territory with the same level of accuracy from North to South;
• they must be certified, in other words they have to come from an official entity who can provide and state their validation;
• they must have the necessary data for further integration with other databases.

For each of the validated database suitable to storage, a form has been filled (a different one from the metadata form) that sums up the cartographic characteristics of each database, briefly describing both geometrical and thematic aspects.
With the help of these forms the logical structures of the data bank has been developed.
The databases have been organized by "concept" ; this include the relative information regarding the format (vector/raster), the theme (argument described in the data bases) and the scale of acquisition.
Such type of structure avoid sidetracking during the data browsing.
Once taken a specific path to acquire the data, the users don’t loose the awareness of the descriptive parameters associated to the data, since those are always carried with the information that is progressively building up during the path.
This doesn’t mean that the path has to be strictly prescriptive, but leaves the capability to access other paths always organized with the same method.

Pictures two shows the tree structure developed for the realization of the databank.
The directories at the tree’s root display the two big data "families" : the raster and the vector families.
Going down the tree, the second layer encountered defines the acquisition scale of the data.
Only three "families" have been considered and consequently only three directory have been structured: big scale, which includes data acquired with the scale range between 1:10.000 (m) and 1:25.000 (m), medium scale that includes data obtained with scale resolution ranging from 1:50.000 to 1:100.000 and at last a small scale that group all the data acquired at a resolution scale of 1:250.000 and below.
Descending further the tree, we find the third layer which stores data according the theme that they describe: for instance in the anthropic directory there are databases that describe the transportation network (roads, highways, railways, ..) developed areas, history center, industrial areas.
Spatial data stored in the Italian seismic survey information system, almost never were in the ArcInfo format, often were ASCII files, or DXF files stored in other operation systems different from UNIX (DOS, NT, ..). Otherwise, when they were already in the ArcInfo format, most of the time they were organized in a different way from the one desired (grouped by province instead by theme with different projection systems). Consequently the data bases implementation in the cartographic databank, has required extraction processes from their original O. S. , of cleaning with the elimination of the redundant information and, in the end, the transformation to ArcInfo coverages or grids with a UTM zone 32. projection.
Each databases has been described both with a metadata form (which contain information about its source identification, its structure, units of measurement, and its accuracy level) and a data dictionary where each data element and its characteristics have been defined: name, physic type, logic type, condition of existence, origin, meaning of the codified fields, and more.
At the present time, the data bank include 77 databases which each of them includes more databases (tab.1).

THE DATA BASES ACCESS

During the wait for the definitive realization of the "access system" to the information and data, which is under development with the subproject named "communication system", we provided to the internal user of the SSN (Italian seismic service), a modular environment for data consulting that allow to get from the databank the desiderate data and also to manipulate them according to the various user’s needs.

The contest analysis in pic. 3 shows how the SSN internal utilization demand is extremely differentiated both for the requirements (in every office the operative process and decisional process are different) both for the different cultural background between the same users (engineers, architects, geologist, physics, …).
We have therefore chosen to provide a modular operative environment that would allow the users, once terminated the reading and definition of its own "work project", the most possible flexible data bundle in order to produce validated data.
The users have the capability of taking advantage of their own professional skills: in fact is the user himself that define the logic processes of aggregation and data manipulation. The user is furthermore able to change the logic processes regarding the intermediate results obtained during the analysis process.
The "Esri arcview3" software system has been chosen to access the databank.
The "Esri arcview3" software system allows to access the cartographic data bases in its graphics and alpha numeric elements: it provides both basic GIS functions for spatial analysis and also the classical DBRMS operators.
The access is allowed only in the reading mode: the databank information can be retrieved and utilized, but they can not be modified / edited neither new data can be entered without the specific permission of the system databank administrator.
In the next future, following the AIPA directives and using the RUPA (Public Administration unified network), the databank will be made accessible even also through the consolidated technologies belonging to the INTRANET/INTERNET architectures. In fact, upon necessities, it will be possible to export data, using the same technologies procedures of the WEBSERVER/ WEB COMPUTING and the browsing interface type available from different architecture system providers.

CONCLUSION

Within the scope of data acquisition and data manipulation from the different updated database relative to seismic risk evaluation in Italy, we collected and made available, in a consistency way, a lot of information in the SSN databank. A cartographic databank containing almost eighty vector data bases (more then 300 ArcInfo coverage) geo-referenced to UTM zone 32 has been created.
Different tools for the access to the databank will be available: a first layer of access, will allow the medatata form reading, and will help the users in the information research, in this way they will have a detailed picture of all the data relative to the chosen theme. Further access layers have been implemented for different kind of users. These layers allow manipulation of the data in order to produce thematic maps, tables, and other data bases.
Some application, in the ArcInfo environment, have been implemented for the decision supporting during the seismic event management in "Crisis Rooms".
The databases stored in the databank can be used for different tasks, therefore we hope that in the next future the databank will be considered a valid working tool for all the Public Administration Agencies.