A prototype HGIS for managing earthquake data from historical documents

Abstract

Studies regarding historical seismic events occurred during the pre-instrumental era are mostly based on the interpretation of coeval records reporting earthquake effects on humans and buildings as experienced and reported by witnesses. Historical sources typically consist of written documents such as letters, newspapers articles, chronicles and memoirs that survived the passage of time; from these documents and their historical context, seismologists isolate the relevant descriptive information on the effects of a seismic event in a place. This information is required to estimate a macroseismic intensity, in turn, used as input to assess the earthquake parameters such as the epicentre location and magnitude. Historical seismologists feel the need of a system for organizing the huge amount of data retrieved in their research, and able to keep trace of the complex relations among these data. A tool addressing these needs may well be used to perform the opposite action: being able to trace back each step of the research procedure, enabling seismologists checking the reliability of the background data, spotting potential errors or potential misinterpretations, and, possibly, to enrich and consolidate the description of an earthquake. This work, carried out with the collaboration of an experienced historical seismologist, investigates the peculiar needs of this field of research and proposes new tools, which are based on a Geographical Information System (GIS). Finally, a prototype system is presented. This solution enables to store, manage and analyse spatial and thematic data related to historical earthquakes, and integrates the relevant data resulting from seismic studies and from their original source documents. In particular, the conceptual model of the GIS spatial database is described and some examples of maps and queries are discussed for a case study represented by two earthquakes which occurred in Locris (Greece) on the 20th and 27th April 1894.