With the advent of high-quality digital seismograms from the Global Digital Seismic Network, and with our increasing analytic and computational ability to invert such data for earthquake source characteristics, it is becoming possible to probe more finely the asperity size distribution during rupture of an earthquake. In order to gain a better understanding of the effect of tectonic setting on rupture process, we propose to investigate source characteristics of large earthquakes at periods of 1 to 30 seconds. We wish to compare source spectra, source time functions, and spatial distribution of moment release for shallow subduction earthquakes from several different zones, outer-rise earthquakes that occur within oceanic lithosphere seaward of subduction zones, and intermediate and deep earthquakes.
