We use seismographic data from 12 local, shallow earthquakes of magnitude MN 1.0–3.1 that occurred near Sudbury, Ontario, recorded at three stations within 30 km of the source, to examine ground-motion attenuation at close distances. This is an important issue for development of ground-motion prediction equations in eastern North America and for the inference of earthquake source parameters from regional earthquake observations. We show that high-frequency (3–10 Hz) horizontal-component ground motions decay at a geometric spreading rate of approximately R-1.3 in the first 25–30 km from the earthquake source (where R is the hypocentral distance). This is in agreement with the geometric spreading rate determined by Atkinson (2004) and used in the ground-motion prediction equations of Atkinson and Boore (2006). Vertical-component ground-motions in this distance range appear to decay at a slightly slower rate of R-1.1.

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