2016年新西兰7.8级大地震GPS观测结果与弹性回跳模型

Results of GPS Observations for M7.8 Earthquake in 2016 in New Zealand and Discussion on Elastic Rebound Model

  • 摘要: 利用http://geodesy.unr.edu网站发布的新西兰和澳大利亚部分GPS连续观测站的数据处理结果,获取2016-11-13新西兰7.8级大地震同震位移、区域参考框架震前和震后水平位移。新西兰CMBL和KAIK站及日本USUD和TSKB等站的水平位移向量时间序列图直观且清楚地显示,同一GPS站同震水平位移方向和震前积累水平位移的总方向相反,同震水平位移是震前积累的水平位移的回跳或弹性回跳,因此,震前积累的水平位移是地震前兆。利用丰富的GPS观测结果讨论回跳或弹性回跳模型。分析东日本9.0级大地震GPS观测结果,表明,震前震中区一主应变为东西向的压缩,而地震的发生和同震形变是地震断层剪切形变所致。这与岩石破裂实验、应变理论和地震机制研究结果一致。

     

    Abstract: the coseismic and the preseismic displacements in the regional reference frame were obtained for the M7.8 earthquake on Nov. 13, 2016 in New Zealand based on time series of coordinates at continuous GPS observation stations, available from http://geodesy.unr.edu, in New Zealand and Australia. horizontal displacement time series vectors at CMBL and KAIK in New Zealand and at USUD and TSKB in Japan are shown. The vector time series show clearly with direct visual effect that the coseismic horizontal displacements were sudden and dramatic, and opposite to the accumulated preseismic horizontal displacements. These represent a rebound or elastic rebound of the accumulated preseismic horizontal displacements. Therefore, the accumulated preseismic horizontal displacements were precursors to the earthquakes. Results produced from the abundant GPS observations are used to discuss the rebound and elastic rebound models. Detailed reanalysis on the results of GPS observations of the M9.0 Tohoku earthquake in Japan shows that one principal strain in the region at and around the epicenter was dominated by compression in the east direction before the earthquake. Moreover, the earthquake and the coseismic displacements were the result of shear rupture at the earthquake faults. This agrees with test of rock failure results, strain analysis, and consistent with earthquake mechanisms.

     

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