MAHA: A comprehensive system for the storage and visualization of subsoil data for seismic microzonation

MAHA is a database-centred software system for the storage and visualization of subsoildata used for the production of seismic microzonationmaps in Italy. The application was implemented using open source software in order to grant its maximum diffusion and customization. A conceptual model of the subsoil, jointly developed by the Italian National Research Council and the National Department of Civil Protection, inspired the structure of the underlying database, consisting of 15 tables, 3 of which of spatial nature to accommodate geo-referenced data associated to points, lines and polygons. A web-GIS interface acts as a bridge between the user and the database, drives the input of geo-referenced data and enables the users to formulate different types of spatial queries. A series of forms designed ''ad hoc'' and enriched with combo boxesprovide guided procedures to maximize the fluency of data entry and to reduce the possibility of erroneous typing. One of these procedures helps to transform the descriptions of the geological units (granular materials), given in technical paper documents by using a conversational style, into standardized numeric codes. Summary reports, produced in the pdf format, can be generated through decoding and graphic display of the parameters previously entered in the database. MAHA was approved by the national commission for seismic microzonationestablished by the Italian Prime Minister and, in the next years, it is expected to significantly support the entire process of map production in the urban areas more exposed to seismic hazard.