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通过合成孔径雷达(SAR)干涉测量和全球定位系统(GPS)数据的反演,并结合远震宽频带和近场强震记录,研究了1999年8月17日伊兹米特地震滑动的时空分布。地表位错是作为附加的约束使用的,特别着重分析了不同数据集的分辨率。我们使用了四段有限断层模型和非线性反演方法,允许滑动的幅度、方向和持续时间以及破裂速度是可变的。通过人工合成数据的反演我们发现,最佳空间分辨率可出现在断层模型的上半部(上部12kin),那里,干涉测量的合成孔经雷达数据覆盖好(破裂的西半部),并接近GPS和强震台站。发现远震数据的分辨率较低,它相当均匀地分布在断层模型中。与分别反演相比,把所有数据集进行联合反演能提高分辨能力,并可以对滑动的时空分布给出相当好的描述。我们的研究显示了在评估地震动态模型的可靠性中分辨率检验的重要性,并证实了单一类数据的极好拟合不一定就意味着完好地恢复地震的动态特性。伊兹米特破裂几乎是纯右旋走滑的,以中心凹凸体的双侧破裂占优势,该凹凸体的位置在29.7°E(格尔居克市以西约10km)和30.5°E(萨潘贾湖东边)之间,在深为6～12 km的范围其滑动达到6～8 m。发现破裂的西端在亚洛瓦市附近,但大幅值的滑动结束在29.7E(赫赛克三角洲以东10 kin)附近。满足所有数据集的第二个人幅值滑动区,位于朝迪兹杰市方向的更东部,具体是在30.7°E和31.1°E之间(卡拉德尔和迪兹杰断层)。这一东滑动区由一个滑动明显减少的区域把它与中心主凹凸体分开,数据很难约束它,然而,迪兹杰市附近的强震台站帮助测定了31.1°E附近6～12 km深的大滑动区的位置。由联合反演得到的总地震矩为2.4×10~(27)dyne cm。大部分能量在小于15s的短时间内就释放了,这与中心凹凸体的双侧破裂相一致。破裂传播相对来说是均匀的,并快速向西传播,破裂速度接近3.5 km/s。向东传播的大滑动初期比较慢,但在破裂成核后10s的短时间内加速。15s后,向东传播的速度减小到小于2 km/s,在20s以后,破裂以振幅来说几乎消失。然后破裂传播在最东的卡拉德尔断层和迪兹杰断层段继续进行,位置在30.7°E以东,传播时间从22s到50s。对本研究中所考虑波形的模拟,不需要超剪切破裂传播。3个月之后发生的迪兹杰地震(1999年11月12日,M_w7.2)的震源位置紧挨着伊兹米特地震最东滑动区。
Through the synthetic aperture radar (SAR) interferometry and GPS data inversion, combined with teleseismic broadband and near-field strong-motion records, the space-time of the Izmit earthquake on August 17, 1999 was studied distributed. Surface dislocations are used as additional constraints, with particular emphasis on the resolution of different data sets. We used a four-segment finite-fault model and a non-linear inversion method that allowed the magnitude, direction and duration of slippage and the rate of rupture to be variable. From the inversion of the synthetic data we found that the best spatial resolution can appear in the upper half of the fault model (upper 12 km) where the synthetic aperture of the interferometry is covered by radar data (the western half of the rupture) and Close to GPS and strong earthquake stations. The resolution of teleseismic data is found to be low, and it is fairly evenly distributed in the fault model. Compared with separate inversion, the joint inversion of all data sets can improve the resolving power and give a fairly good description of the spatiotemporal distribution of slippage. Our study shows the importance of the resolution test in assessing the reliability of a seismic dynamic model and demonstrates that an excellent fit of a single class of data does not necessarily mean that the dynamic properties of the earthquake are well restored. The Izmit break was almost purely dextral strike-slip, dominated by bilateral ruptures of the central asperities at 29.7 ° E (about 10 km west of Gelg City) and 30.5 ° E East of Panjia Lake), sliding 6 to 8 m deep in the range of 6 to 12 km. The ruptured western end was found near Yalova city, but the sharp slide ended at 29.7E (10 kin east of the Szechenyi Delta). The second personal magnitude slip zone for all datasets, located further east of the city of Dzou, is between 30.7 ° E and 31.1 ° E (the Caledal and Dizzy Faults). The eastern sliding zone is separated from the central main asperity by a region with a significantly reduced slip, which is hard to be constrained by the data. However, the strong ground stations near the city of Dijie helped to measure the 6-12 km near 31.1 ° E The location of the deep big sliding area. The total seismic moment obtained by the joint inversion is 2.4 × 10 ~ (27) dyne cm. Most of the energy is released in a short time of less than 15s, which is consistent with the bilateral rupture of the central asperities. The rupture propagation is relatively uniform and rapidly propagates to the west with ruptures approaching 3.5 km / s. The large slippage propagating eastward was slow at first, but accelerated shortly after 10 s after nucleation. After 15s, the propagation to the east decreased to less than 2 km / s, and after 20s, the rupture almost vanished in amplitude. Then the propagation of the rupture continued over the easternmost Caladium fault and the Dudje fault zone, east of 30.7 ° E, and from 22 s to 50 s. Simulation of the waveforms considered in this study does not require super-shearing propagation. The source of the Dijet earthquake (November 12, 1999, Mw7.2), which occurred three months later, is located next to the easternmost sliding zone of the Izmit earthquake.