Global and along-strike variations of source duration and scaling for intermediate-depth and deep-focus earthquakes

The systematic behavior of earthquake rupture as a function of earthquake magnitude and/or tectonic setting is a key in our understanding of the physical mechanisms involved during earthquake rupture. Geophysical evidence suggests that although deep earthquakes - including intermediate-depth and deep - are similar to shallow ones, the mechanism involved during deep earthquakes is different from that of shallow ones. In particular, the magnitude and depth dependence of scaled duration, a measure of earthquake rupture duration, has led to controversy of what controls deep earthquake behavior. Here we estimate scaled source durations for 600 intermediate-depth and deep-focus earthquakes recorded at teleseismic distances and show deviation from self-similar scaling. No depth dependence is observed which we interpret as due to little differences between intermediate-depth and deep-focus earthquake mechanisms. The data show no correlation between durations and plate age or thermal parameters, suggesting that the thermal properties of the plate have little effect on source durations. We nevertheless report differences in average source duration and scaling between subduction zones and along-strike variations of source durations that more closely resemble the geometry of subduction (flat or steep subduction) rather than plate age.