Centroid single force inversion of seismic waves generated by landslides
Centroid single force inversion of seismic waves generated by landslides
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DOI：
10.1029/jb094ib09p12363
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发表时间：
1989-09
影响因子：
--
通讯作者：
H. Kawakatsu
中科院分区：
文献类型：
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作者：
H. Kawakatsu
本文对Dziewonski等（1981）的矩心矩张量（CMT）波形反演方法进行了改进，使之适用于分析由“单力”事件（如1980年圣海伦斯火山爆发引起的巨大滑坡）产生的长周期地震波。我们称之为质心单力（CSF）反演的方法。作为反演的结果，我们得到的时空质心和三个分量的矢量，我们称之为CSF矢量，这是地震点源的滑坡表示，其方向是相反的滑动方向。CSF矢量的最大值测量滑坡的整体大小，由MCSF = MD给出，其中M是滑动物体的质量，D是滑动距离。我们应用CSF反演所产生的1980年圣海伦火山事件，1975年Kalapana地震，和1974年Mantaro滑坡，使用地震图从GDSN，IDA和HGLP网络的长周期面波。圣海伦斯事件的CSF解与实际地质观测结果非常一致，证明了CSF反演的有效性。Kalapana事件的CSF解决方案与整体波形的拟合度并不比CMT解决方案更好。然而，由于CMT解决方案并不能解释所观察到的乐甫波辐射模式，它可能是必要的调用这两种类型的机制的组合这一事件。虽然Mantaro事件的CSF解的几何形状（力的方向）与实际滑坡一致，但MCSF比地质观测估计的滑坡质量和移动距离所预期的小约5倍。这种差异可能表明，要么相对地震性质的滑坡或总体积的滑坡被高估。与单站CMT反演类似，单站CSF反演也是稳定和有用的。
The centroid moment tensor (CMT) waveform inversion method of Dziewonski et al. (1981) is modified to analyze long period seismic waves generated by “single force” events such as the gigantic landslides associated with the 1980 eruption of Mount St. Helens. We refer to the method as centroid single force (CSF) inversion. As the result of the inversion we obtain the spatio-temporal centroid and three components of a vector we call the CSF vector, which is the seismic point source representation of a landslide and whose direction is the opposite of the direction of sliding. The sealer magnitude of the CSF vector measures the overall size of the landslide and is given by MCSF = MD, where M is the mass of the sliding object and D is the sliding distance. We apply CSF inversion to the long period surface waves generated by the 1980 Mount St. Helens event, the 1975 Kalapana earthquake, and the 1974 Mantaro landslide, using seismograms from the GDSN, IDA and HGLP networks. The CSF solution for the St. Helens event is remarkably consistent with the actual geological observations and proves the efficacy of CSF inversion. The CSF solution for the Kalapana event does not fit the overall waveforms better than the CMT solution does. However, because the CMT solution does not explain the observed Love wave radiation pattern, it may be necessary to invoke a combination of both types of mechanism for this event. Although the geometry of the CSF solution (the direction of the force) for the Mantaro event is consistent with the actual landslide, MCSF is about 5 times smaller than that expected from the mass and travel distance of the landslide estimated by geological observations. This discrepancy may suggest either the relatively aseismic nature of this landslide or that the total volume of the slide was overestimated. By analogy to single station CMT inversion, single station CSF inversion also appears to be stable and useful.