Inversion of complex body waves
Inversion of complex body waves
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发表时间：
1982-04
影响因子：
3
通讯作者：
M. Kikuchi;H. Kanamori
中科院分区：
文献类型：
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作者：
M. Kikuchi;H. Kanamori
我们已经开发了一种方法，反演地震体波，以确定地震的机制和破裂模式。破裂模式表示为分布在断层面上的一系列子事件。这种方法是我们以前的方法，其中子事件机制是固定的扩展。在新的方法中，子事件机制是从数据中确定的，并允许在序列中发生变化。然而，当子事件机制允许变化时，反演往往变得不稳定，因为子事件的机制、时间和位置之间存在复杂的权衡。许多不同的子事件序列可以同样好地解释相同的数据，确定允许的解决方案的范围是很重要的。必须对解施加一些约束以稳定反演。我们已经开发了一个程序，以探索允许的解决方案和适当的约束的范围。在这个过程中，在τ - I平面上构建网格点网络，其中τ和I分别是子事件的开始时间和距震中的距离;在所有网格点处确定最佳拟合子事件。然后计算每个子事件的合成波形与观测波形之间的相关性。作为τ和I的函数的相关性以及在每个τ - I网格点处计算的最佳拟合机制描绘了允许解的特征，并有助于决定对解施加的适当约束。用1976年危地马拉地震的数据说明了该方法。
We have developed a method that inverts seismic body waves to determine the mechanism and rupture pattern of earthquakes. The rupture pattern is represented as a sequence of subevents distributed on the fault plane. This method is an extension of our earlier method in which the subevent mechanisms were fixed. In the new method, the subevent mechanisms are determined from the data and are allowed to vary during the sequence. When subevent mechanisms are allowed to vary, however, the inversion often becomes unstable because of the complex trade-offs between the mechanism, the timing, and the location of the subevents. Many different subevent sequences can explain the same data equally well, and it is important to determine the range of allowable solutions. Some constraints must be imposed on the solution to stabilize the inversion. We have developed a procedure to explore the range of allowable solutions and appropriate constraints. In this procedure, a network of grid points is constructed on the τ - I plane, where τ and I are, respectively, the onset time and the distance from the epicenter of a subevent; the best-fit subevent is determined at all grid points. Then the correlation is computed between the synthetic waveform for each subevent and the observed waveform. The correlation as a function of τ and I and the best-fit mechanisms computed at each τ - I grid point depict the character of allowable solutions and facilitate a decision on the appropriate constraints to be imposed on the solution. The method is illustrated using the data for the 1976 Guatemala earthquake.