Seismic Energy: Measurement, Mechanism Dependence, and Scaling

该项目计划研究地震能量的测量、机制依赖和尺度。对地震能量的估计有很大的潜在误差，同一地震的不同估计通常相差10倍或更多，不同研究报告的地震能量的标度特性和震源机制相关性是相互矛盾的。一些研究发现，地震应力降(通过将地震能量除以地震矩来计算)随地震大小而变化，而另一些研究则没有发现变化。一些研究发现地震应力降随震源机制的系统性变化，而另一些研究发现不存在机制依赖性。几项研究表明，远震对地震能量的估计大约比近震源估计低一个数量级，但这种差异的来源尚未确定和纠正。地震能量很难估计，因为它是震源强度的宽带量度，因此必须在很宽的频率范围内考虑和校正波传播效应和震源激励。在拟议的研究中，这项研究将利用现代宽带数字数据来解决地震能量估计中的差异。这些改进的估计将被用来测试可能的尺度和机制依赖性，并探索它们对地震过程的影响。

This project proposes to study the measurement, mechanism dependence, and scaling of seismic energy. Estimates of the seismic energy have large potential errors, with different estimates for the same earthquake commonly varying by a factor of 10 or more, and the scaling properties and focal mechanism dependence of seismic energy reported by different studies are contradictory. Some studies find that the earthquake stress drop (calculated by dividing seismic energy by the seismic moment) varies with earthquake size, while other studies find no variation. Some studies find a systematic variation of earthquake stress drop with focal mechanism, while others find no mechanism dependence. Several studies have suggested that teleseismic estimates of seismic energy are about an order of magnitude lower than near-source estimates, yet the source of this discrepancy has not been identified and corrected. Seismic energy is difficult to estimate because it is a broadband measure of the strength of the earthquake source and hence one must account and correct for both wave propagation effects and source excitation over a wide frequency range. In the proposed study, the research will take advantage of modern broadband digital data to resolve discrepancies in estimates of the seismic energy. These improved estimates will be used to test for possible scaling and mechanism dependence and explore their implications for the earthquake process.