Comparison of Earthquake Source Spectra and Attenuation in Eastern North America and Southeastern Australia

Abstract

Abstract The paucity of ground-motion data in Stable Continental Regions (SCRs) remains a key limitation when developing relations that seek to predict effects of strong ground-shaking from large damaging earthquakes. It is desirable to combine data from more than one SCR in order to increase database size, but this raises questions as to whether the source and attenuation properties of the SCRs are equivalent. We merge recently- compiled spectral-amplitude databases from small-to-moderate events (moment magnitudes 2.0 ≤ M ≤ 5.0) in both southeastern Australia and eastern North America in order to compare the key characteristics of ground motion in these two regions. Both are SCRs, but are widely separated, spatially and in tectonic history. We statistically compare ground motions by plotting mean and standard deviations of spectral amplitudes for data grouped in magnitude and distance bins. These comparisons show that the source and attenuation properties of the two regions are very similar, particularly at shorter hypocentral distances