Izmit earthquake postseismic deformation and dynamics of the North Anatolian Fault Zone
Izmit earthquake postseismic deformation and dynamics of the North Anatolian Fault Zone
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DOI：
10.1029/2008jb006026
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发表时间：
2009-08-25
影响因子：
3.9
通讯作者：
Reilinger, R. E.
中科院分区：
文献类型：
--
作者：
Hearn, E. H.;McClusky, S.;Reilinger, R. E.
我们模拟了1999年至2003年的震后变形在1999年伊兹米特和Duzce地震破裂周围的地区，使用三维粘弹性有限元法。我们的模型证实了早先的研究结果，即伊兹米特地震前几个月内的地表变形主要是由于伊兹米特地震破裂上和下的稳定摩擦后滑。然而，需要第二次变形过程以适应数月后的表面变形。下地壳和（或）上地幔的粘弹性松弛（粘性约为2至5 × 10（19）Pa·s）改善了模型对后期GPS站点速度的拟合。然而，对于线性粘性流变学，这一范围的值是不一致的高度本地化的震间变形周围的北安纳托利亚断层带（NAFZ），以及观察到的地震序列之前。这个问题的最简单的解决方案是假设松弛材料的有效粘度在大地震后随着时间的推移而增加，也就是说，它具有幂律或伯格体（瞬态）流变学。在地幔中具有两种特征粘度（2至5 × 10（19）Pa·s和至少2 × 10（20）Pa·s）的Burger体流变学与整个地震周期中NAFZ周围的变形一致。
We have modeled postseismic deformation from 1999 to 2003 in the region surrounding the 1999 Izmit and Duzce earthquake ruptures, using a three-dimensional viscoelastic finite element method. Our models confirm earlier findings that surface deformation within the first few months of the Izmit earthquake is principally due to stable frictional afterslip on and below the Izmit earthquake rupture. A second deformation process is required, however, to fit the surface deformation after several months. Viscoelastic relaxation of lower crust and/or upper mantle with a viscosity of the order of 2 to 5 x 10(19) Pa s improves the models' fit to later GPS site velocities. However, for a linear viscous rheology, this range of values is inconsistent with highly localized interseismic deformation around the North Anatolian Fault Zone (NAFZ) that was well observed prior to the earthquake sequence. The simplest solution to this problem is to assume that the effective viscosity of the relaxing material increases with time after large earthquakes, that is, that it has a power law or Burger's body (transient) rheology. A Burger's body rheology with two characteristic viscosities (2 to 5 x 10(19) Pa s and at least 2 x 10(20) Pa s) in the mantle is consistent with deformation around the NAFZ throughout the earthquake cycle.