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The ground motion database file (.db) stores the following information:
1.The records' metadata fields.
2.Information about the collection objects, that act like virual folders, and are used to organize the records,
3.Computed response spectra and intensity measures of the records
The acceleration histories are NOT saved within the database. Instead, the database contains information about the location (path and files names) of the acceleration data on the user's disk. This helps keep the size of the database (.db) file manageable. Once the spectra of the records are computed by the program, they are automatically saved in the database (the user can set the Options for deciding which spectral quantities to automatically save to the database). This makes it possible to:
•Quickly load the cached spectra from the database without having to recompute them every time.
•Perform ground motion selection with records even if the acceleration history files are not available on disk (this makes it handy, for example, to search the NGA database, or other databases that cannot be fully downloaded or are too large to distribute); The user could then download only the records they need.
Keeping the above folder structure in mind, now you know that all the records in the ground motion library live in the ground motion database file (QMDB.db), so don't move it, delete it or rename it because QM won't be able to find it. If you DO want to move this file, it is possible to specify within QuakeManager that the location has changed. This is done under the Options dialog (accessed from the file menu), which offers two file locations that can be customized. The first location is a default folder for all ground motion data (default is C:\GMLibrary\), and the other is the location of the Ground Motion Database (GMDB) file (default is C:\GMLibrary\QMDB.db).
So when you click on a collection in the GM Library, QuakeManage retrieves data from the Database file (.db) and shows the records contained within it. If the ground motion acceleration files are available on disk, QM will find them, for example LA01, and load their acceleration history data and show it on the acceleration chart. QuakeManager will also automatically compute the spectra and intensity measures on the fly, which will then be automatically saved to the database and made available for future search. This makes the database a Self-Building Database, because it is able to build itself internally automatically without the need for external analysis software.
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