D53 S. Miguel Geological Hazard Database (MIHADA)– CVUA

Introduction:

Geological hazards in the Azores archipelago include earthquakes, volcanic eruptions, degassing phenomena and landslides, being the cause of thousands of deaths and severe damage and loss. To reduce the impact of future events it is necessary to improve the emergency response and reinforce land-use planning. This gave rise to the development of AZORIS, a GIS database for hazard assessment and risk analysis, based on the ArcGIS® software from ESRI and installed over a Windows 2000® platform from Microsoft.

Database organization:

Information included in the AZORIS database was obtained (1) through the interpretation of historical documents, (2) during recent fieldwork campaigns (e.g. mapping of volcanic centres and associated deposits, faults, dikes, soil degassing anomalies, landslides) and (3) from the existent monitoring networks (e.g. seismic, geodetic, fluid geochemistry).

At present this computer-based system comprises nine main dynamic data sets (Geographical and socio-economic, Civil protection, Geological and geomorphologic, Landslides, Volcanological, Seismological, Geodetic, Fluid geochemistry and Meteorological) where elemental, monitoring and historical data are grouped in layers (Fig. 1).

The logical structure of the database was conceived in order to facilitate interactivity between data sets and to guarantee the evolution of the system, as determined by the input and the generation of new and more detailed information. Archive organization was designed taking into account regional and local aspects of geological hazard. In order to ensure consistency of the database and the quality of the data within it, an internal process of validation was included.

Fig. 1: Organizational scheme of the information available in AZORIS

With this GIS database, data can be accessed and analysed interactively in order to produce new and combined information. In the present case, risk analysis comprises hazard assessment and vulnerability evaluation using diverse methodologies and precise predicting models (Fig. 2). The generated data sets results from spatial, 3-D and geostatistical analysis and are the main frames for risk assessment and management.

Fig. 2: Example of an output from AZORIS: a buildings vulnerability map for Povoação village considering seismic activity.

A major step in the development of the system is related to the application of models for hazard and vulnerability assessment. This will lead to the definition of risk zones based on critical values that can be used for emergency and land-use planning. Another potential of AZORIS results from its link to the monitoring networks operated by the CVUA

Literature produced:

Gaspar, J.L., Goulart, C., Queiroz, G., Silveira, D. and A. Gomes, Dynamic structure and data sets of a GIS database for geological risk analysis in the Azores volcanic islands, Natural Hazards and Earth System Sciences, 4: 233–242, SRef-ID:1684-9981/nhess/2004-4-233, 2004.