Development of a database and visualization system integrating various models of seismic velocity structure and subducting plate geometry around Japan

Abstract

To estimate strong ground motions caused by future earthquakes in Japan and to more accurately predict seismic hazards and tsunamis, it is necessary to accurately model the geometry of the subducting plate and the seismic velocity structure around Japan, particularly in offshore areas. Although various seismic velocity structure and plate boundary models have been proposed around Japan, they are all managed individually and differ in extent, data type, and format. Ensuring consistency among those models requires knowledge of their spatial distribution around the subduction zones of Japan. Here, we describe a database system to store and serve various velocity structure and plate geometry datasets from around Japan. Seismic structure models in this database include 3D seismic velocity models obtained by seismic tomography, 3D plate geometry models, 2D seismic velocity structure models, 2D plate geometry models obtained by offshore seismic surveys, and hypocenter distributions determined by offshore observations and the Japan Meteorological Agency. Using this database (currently available only in Japanese), users can obtain data from several structural models at once in the form of the original model data, equal-interval gridded data in a text file, and Keyhole Markup Language (KML) data. Users can grasp the distributions of all available seismic models and hypocenters using a web-based interface, simultaneously view various models and hypocenters as KML output files in Google Earth, and easily and freely handle the structural models in a selected area of interest using the gridded text-file output data. This system will be useful in creating more accurate models of the geometries of the subducting plate and the seismic velocity structure around Japan. [Figure not available: see fulltext.].