Source Models of Two Large Intraslab Earthquakes from Broadband Strong Ground Motions
Source Models of Two Large Intraslab Earthquakes from Broadband Strong Ground Motions
复制标题
宽带强地震动两次大型板内地震的震源模型
DOI：
10.1785/0120030033
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发表时间：
2004
影响因子：
3
通讯作者：
T. Sasatani
中科院分区：
文献类型：
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作者：
N. Morikawa;T. Sasatani
根据强震记录，我们建立了沿南千岛-北海道弧线的两次大地震(1993-Kushiro-oki和1994-Hokkaido Toho-oki地震)的震源模型；震源模型很好地解释了观测到的宽带强地面运动。我们假定断裂面上的矩形凹凸体的分布，并将经验Green9s函数方法应用于由凹凸体合成强地面运动。通过将合成波形(位移、速度和加速度的时间历程)和频谱与观测结果进行匹配来估计粗糙度参数(面积和应力降)。与具有类似地震矩的内陆和板块边界地震相比，我们的震源模型具有以下特点：(1)总的粗糙区小得多，(2)应力降极高(约200-400兆帕)。这表明，台内大地震在短时间内从较小的区域辐射出地震能量。这种破裂过程导致了极强的短周期地震波辐射。最后，我们确认了两次实验室内地震的外部(整个断层的大小、地震矩和加速度源谱的短周期水平)和内部断层参数(凹凸体的面积和应力降)之间的相关性。
We construct source models of two large intraslab earthquakes (the 1993 Kushiro-oki and 1994 Hokkaido Toho-oki earthquakes) along the southern Kurile–Hokkaido arc based on strong motion records; the source models well explain observed broadband strong ground motions. We assume a distribution of rectangular-shaped asperities on a fault plane and apply the empirical Green9s function method to the synthesis of strong ground motions from the asperities. The asperity parameters (area and stress drop) are estimated by matching the synthetic waveforms (displacement, velocity, and acceleration time histories) and spectra to the observed ones. Our source models have the following characteristics compared with those of inland and plate-boundary earthquakes having a comparable seismic moment: (1) the total asperity area is much smaller, and (2) the stress drop is extremely high (about 200–400 MPa). These indicate that the large intraslab earthquakes radiate seismic energies from a small area in a short time. This rupture process results in extremely strong radiation of short-period seismic waves. Finally, we confirm a correlation between outer (entire fault size, seismic moment, and short-period level of the acceleration source spectrum) and inner fault parameters (areas and stress drops of asperities) for the two intraslab earthquakes.
Sawada, Y.：“日本西南部山阴地区白垩纪至中新世火成岩的 Nd-Sr 系统学。”
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