id="p-1">We estimate the m>am>rms‐stress drop, mula" id="inline-formula-1">mg class="inline-graphic" alt="Graphic" src="211/embed/inline-graphic-1.gif" />, (id="xref-ref-20-1" class="xref-bibr">Hanks, 1979) using acceleration time records of 59 earthquakes from two earthquake sequences in eastern Honshu, Japan. These acceleration‐based static stress drops compare well to stress drops calculated for the same events by id="xref-ref-9-1" class="xref-bibr">Baltay m>et al.m> (2011) using an empirical Green’s function (eGf) approach. This agreement supports the assumption that earthquake acceleration time histories in the bandwidth between the corner frequency and a maximum observed frequency can be considered white, Gaussian, noise. Although the mula" id="inline-formula-2">mg class="inline-graphic" alt="Graphic" src="211/embed/inline-graphic-2.gif" /> is computationally simpler than the eGf‐based mula" id="inline-formula-3">mg class="inline-graphic" alt="Graphic" src="211/embed/inline-graphic-3.gif" />‐stress drop, and is used as the “stress parameter” to describe the earthquake source in ground‐motion prediction equations, we find that it only compares well to the mula" id="inline-formula-4">mg class="inline-graphic" alt="Graphic" src="211/embed/inline-graphic-4.gif" /> at source‐station distances of ∼20 km or less because there is no consideration of whole‐path anelastic attenuation or scattering. In these circumstances, the correlation between the mula" id="inline-formula-5">mg class="inline-graphic" alt="Graphic" src="211/embed/inline-graphic-5.gif" /> and mula" id="inline-formula-6">mg class="inline-graphic" alt="Graphic" src="211/embed/inline-graphic-6.gif" /> is strong. Events with high and low stress drops obtained through the eGf method have similarly high and low mula" id="inline-formula-7">mg class="inline-graphic" alt="Graphic" src="211/embed/inline-graphic-7.gif" />. We find that the inter‐event standard deviation of stress drop, for the population of earthquakes considered, is similar for both methods, 0.40 for the mula" id="inline-formula-8">mg class="inline-graphic" alt="Graphic" src="211/embed/inline-graphic-8.gif" /> method and 0.42 for the mula" id="inline-formula-9">mg class="inline-graphic" alt="Graphic" src="211/embed/inline-graphic-9.gif" />, in log10 units, provided we apply the ∼20 km distance restriction to mula" id="inline-formula-10">mg class="inline-graphic" alt="Graphic" src="211/embed/inline-graphic-10.gif" />. This indicates that the observed variability is inherent to the source, rather than attributable to uncertainties in stress‐drop estimates.
id="p-2">m>Online Material: m>Earthquake catalog including additional source parameters.
