The Spectral Matching (QuakeMatch) provides the ability to modify a record or suite of records in order to achieve an improved fit to the target spectrum, beyond what can be achieved by scaling alone. QuakeMatch incorporates both tight and mean spectral matching to adjust ground motion suites for an improved fit to the target. Furthermore, the implemented mean spectral matching technique helps in maintaining record characteristics (such as velocity pulse) and controlling variability while meeting code requirements.

QuakeManager offers two methods for spectral matching:

1.Tight Matching: This is the conventional spectral matching typically performed, where each ground motion is modified such that its spectrum perfectly matches the target. The tight matching to the target spectrum over a wide frequency range minimizes the potential amplification of higher modes (at short periods) and significantly reduces the variability in spectral ordinates. [8]

2.Mean Matching:  Is a hybrid spectral matching method, where records in the suite are each slightly modified such that the average (and optionally the dispersion) of the suite perfectly matches the target. Mean Matching preserves the peaks and valleys, natural dispersion, characteristic period and energy content of the records. This method eliminates the peaks and valleys of the average suite spectrum and hence, minimizes the amplification effects on higher modes (on average for the suite), and is also better at preserving the natural characteristics of the records. [8]

Spectral matching is performed using an iterative process of adding wavelets to the acceleration time history until a suitable solution is achieved. The algorithm follows principles that are well established as proposed in several papers [9] [10] [11], and as implemented in the software RSP-MATCH [9] [10].

QuakeMatch adapts the method used in RSP-MATCH while adding several improvements that improve speed and stability, and add additional features including the ability to match directly to RotD100 and RotD00, which was based on the method proposed by [12].

Figure: Tight Spectral Matching

Figure: Mean Spectral Matching

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