Inversion of strong motion seismograms for the source process of the Naganoken-Seibu earthquake of 1984
Inversion of strong motion seismograms for the source process of the Naganoken-Seibu earthquake of 1984
复制标题
1984年长野根-西武地震震源过程的强震图反演
DOI：
10.1016/0040-1951(87)90022-9
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发表时间：
1987
期刊：
影响因子：
2.9
通讯作者：
Naoya Mikami
中科院分区：
文献类型：
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作者：
M. Takeo;Naoya Mikami
本文利用距震中100公里以内的强震记录，详细研究了1984年野野之根-西武6.8级地震的震源过程。应用一种新的反演方法对强震记录进行了分析。我们用一个由一定数量的子断层组成的模型对问题进行了参数化处理，在这个模型中，断层在任意时刻以任意大小开始破裂，我们成功地得到了断层上的位错分布和破裂传播的特征，破裂从断层中部的最浅点开始，然后在大约3s的时间内传播到整个震源区。由最终解估算的总地震矩为3 × 1025 dyne· cm。断层面上位错分布不均匀，最大值约为1.5 ~ 2 m。最大的位错发生在近表面区域。在断层较深的部分，位错似乎很小。断层中心和浅部余震较少，大余震（M> 4.0）多位于断层深部。这些结果表明，在应力集中的断层未破裂区，余震活动最高。根据断层上位错的分布，估计震源区的大小约为12 km（长）× 6 km（深），利用最终的震源模型，在没有记录的地点估计了周期大于1 s的主震地面运动。在Mt.最大位移和速度分别为15和12 cm/s。最大短周期加速度在0.1s周期约300 Gal的山顶。吃吧
The source process of the Noganoken-Seibu earthquake of 1984 (M= 6.8) has been investigated in detail by using strong motion seismograms recorded at stations within 100 km of the epicenter. A new inversion method was applied to analyze the strong motion seismograms. We parameterized the problem by using a model in which the fault was composed of a certain number of subfaults which started rupturing with arbitrary magnitude at arbitrary time, and we have successfully obtained the dislocation distribution and the characteristics of rupture propagation on the fault.The rupture starts at the shallowest point on the central part of the fault and then propagates over the whole source region within about 3 s. The total seismic moment estimated from the final solutions is 3 × 1025dyne · cm. The dislocation is inhomogeneously distributed on the fault plane and reaches a maximum of about 1.5–2 m. The largest dislocation occurs in the near surface region. On the deeper part of the fault, the dislocation seems to be small. There were few aftershocks at the center and on the shallow part of the fault; most of the large aftershocks (M> 4.0) were located on the deeper part of the fault. These results suggest that the aftershock activity was highest on the unruptured regions of the fault where stresses were concentrated. From the distribution of dislocations on the fault, the size of the source area is estimated to be approximately 12 km (length) × 6 km (depth).The main shock ground motions, having periods longer than l s were estimated at sites where no recordings exist by using the final source model. At the summit of Mt. Ontake, the maximum displacement and velocity are 15 and 12 cm/s respectively. The maximum short-period acceleration at the period of 0.1 s is about 300 Gal at the summit of Mt. Ontake.