| The paper describes a potential application of the Expert Tsunami Database (ETDB) for estimation of the long-term tsunami hazard. The ETDB has been developed and is being maintained at the Novosibirsk Tsunami Laboratory under the joint project of the IUGG Tsunami Commission (IUGG/TC) and the International Coordination Group for the Tsunami Warning System in the Pacific (ICG/ITSU). The concept of the ETDB is based on the integration of historical data, numerical models, processing and analyzing tools along with supporting mapping software. These components are embedded inside a specifically developed GIS-type graphic shell providing fast and efficient manipulation of maps, models and data. The ETDB is intended to be a comprehensive source of historical data on tsunami occurrence and coastal manifestation along with additional reference information related to the tsunami problem in the Pacific. Three main parts of the ETDB data storage subsystem are TSUNAMI database, EARTHQUAKE database and GEOGRAPHY database. The TSUNAMI database consists of the catalog of tsunamigenic events in the Pacific (Level I data) and the catalog of historical observations of tsunami run-up heights (Level II data). The collected data can be easily retrieved from the database by a number of criteria and are readily available for further display and analysis. Availability of this large amount of digital data on tsunami run-up heights enables us to develop a special application tailored to specific needs of coastal communities for having long-term estimates of tsunami risk. The approach to the long-term tsunami hazard assessment, implemented in the ETDB software, is based on the statistical analysis of historical run-up observations near a particular site and involves the following four basic steps: (1) selection of a particular coastal area within which available historical run-up observations can be considered as spatially correlated; (2) retrieval of historical run-up measurements from the database, displaying them along the time axis and analyzing their time-spatial relation; (3) plotting the data against the ″wave height - frequency occurrence″ diagram and obtaining the ″height - frequency″ relation by linear regression; (4) calculation of the so-called ″hazard curves″ for the estimation of probability that a particular wave height of H (m) will not be exceeded for the given time interval of T (years). For a particular coastal area, this type of analysis can be interactively made using a special pop-up menu and dialog windows. The results can be immediately displayed on the screen in the form of hazard curves and evaluated by an expert. This analysis can be easily repeated for different subsets of data in order to evaluate its variability depending on the data quality and completeness. Some examples of the ETDB application for the tsunami hazard assessment in the different tsunamigenic areas in the Pacific are presented. |
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