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A. Basic Concepts
A.1 Components vs Triplets
In QuakeManager, there are two types of ground motion records: Components and Triplets.
A Component is recording of ground motion in one direction (e.g. East-West direction).
A Triplet is defined as a set of 3 Components representing motion in three directions (two horizontal and one vertical). Components "1" and "2" are horizontal components, while Component "3" is vertical.
A.2 Record Metadata
Record Metadata are descriptive data that characterize each record. For example, the earthquake (event) name, location (epicenter longitude and latitude), and date of occurrence are all examples of metadata of a record.
Similarly, site information, sensor information, etc, are all metadata.
The QuakeManager ground motion database supports most commonly used ground motion metadata (nearly 200 fields of data).
A.3 Ground Motion Files vs Metadata
The ground motion acceleration history is usually stored in a text file while the metadata are stored in a database. The acceleration data points are not stored in the database, in order to keep the size of the database manageable, and because most users are interested in searching a database for metadata and not for the raw data. The filename and path of the acceleration data file is actually one type of metadata that is stored in the database.
A.4 Ground Motion Spectra
Ground motion spectra are a type of searchable metadata saved in the database. This allows a user to search for ground motions by "Spectral Shape", and find the records with response spectra that best match their target response spectra.
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