The dynamic rupture process of the 1993 Kushiro-oki earthquake
The dynamic rupture process of the 1993 Kushiro-oki earthquake
复制标题
1993年钏路冲地震的动力破裂过程
DOI：
10.1029/95jb00959
复制
发表时间：
1996
影响因子：
--
通讯作者：
M. Takeo
中科院分区：
文献类型：
--
作者：
S. Ide;M. Takeo
我们建立了一个与实测地震图相一致的1993年钏路冲地震（Mw = 7.6）的动态破裂模型。这次地震发生在日本钏路市地下，深度约100公里，余震仅限于俯冲板块中双地震带之间的水平面。我们可以得到很好的近场强震记录。在我们的分析中，运动学反演之后是动态裂缝计算，并且重复这对操作，直到获得数据收敛。在动力计算中考虑了两种不同的动应力降情况，并分别建立了相应的动力学模型。这些条件的差异对结果的影响很小。最后的动力学模型表明，这次地震发生的局部高应力降约40 MPa的俯冲板，这表明该地区之间的双地震带是强大的，足以承受这样的高应力。最终模型中的两个高强度区域之一位于双地震带的上平面附近，并且由于板中应力状态的实质性变化而代表屏障。在主破裂前5 s发生初始破裂的区域，强度和应力降均小于相邻区域。这意味着，在主破裂之前，在初始破裂区域的累积应力已经释放。余震倾向于发生在高强度区附近，有些余震的P波初动与主震相反。
We have constructed a dynamic rapture model of the 1993 Kushiro-oki earthquake (Mw = 7.6) that is consistent with the observed seismograms. This earthquake occurred beneath the city of Kushiro, Japan, at a depth of about 100 km, and the aftershocks are limited to a horizontal plane between a double seismic zone in the subducting slab. Excellent near-field strong-motion records are available. In our analysis, a kinematic inversion is followed by a dynamic crack calculation, and this pair of operations is repeated until convergence to the data is obtained. Two different conditions concerning the dynamic stress drop were considered in the dynamic calculation, and a dynamic model was constructed for each condition. The difference in these conditions has little effect on the results. The final dynamic model shows that this earthquake occurred with a localized high stress drop of about 40 MPa in the subducting slab, which indicates that the region between the double seismic zone is strong enough to sustain such a high stress. One of the two high strength regions in the final model lies near the upper plane of the double seismic zone and represents a barrier due to a substantial change of stress state in the slab. In the region where the initial breaks occurred 5 s before the main rupture, both the strength and the stress drop are smaller than in the adjacent region. This implies that before the main rupture the accumulated stress had already been released in the area of the initial breaks. The aftershocks tend to occur near the high strength area; in some of them, the P wave first-motions are opposite to those of the main shock.