This chapter describes the development of the earthquake catalog for the CEUS-SSC Project. The catalog development consists of four major steps: catalog compilation, assessment of a uniform size measure to apply to each earthquake, identification of dependent earthquakes (catalog declustering), and an assessment of the completeness of the catalog as a function of location, time, and earthquake size. Each of these steps is described in detail in the chapter. The result is an earthquake catalog covering the entire study region defined in Chapter 1 for the time period of 1568 through the end of 2008. Earthquake size is defined in terms of the moment magnitude scale (Hanks and Kanamori, 1979), consistent with the magnitude scale used in modern ground motion prediction equations for CEUS earthquakes.


3.1 Goals for the Earthquake Catalog Development

The catalog of past earthquakes that have occurred in a region is an important source of information for the quantification of future seismic hazards. This is particularly true in stable continental regions such as the CEUS where the causative mechanisms and structures for the occurrence of damaging earthquakes are generally poorly understood, and the rates of crustal deformation are low such that surface and near-surface indications of the buildup and release of crustal stresses are difficult to identify. Because the earthquake catalog will be used to characterize the occurrence of future earthquakes in the CEUS, developing an updated earthquake catalog for the study region was an important focus of the CEUS-SSC Project. The specific goals for earthquake catalog development are described in the following sections.

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