Bouchon Michel, Karabulut Hayrullah
Centre National de la Recherche Scientifique et Université Joseph Fourier, Grenoble, Laboratoire de Géophysique Interne et Tectonophysique, Boîte Postale 53, 38041 Grenoble, France.
Science. 2008 Jun 6;320(5881):1323-5. doi: 10.1126/science.1155030.
Recent studies show that earthquake faults may rupture at speeds exceeding the shear wave velocity of rocks. This supershear rupture produces in the ground a seismic shock wave similar to the sonic boom produced by a supersonic airplane. This shock wave may increase the destruction caused by the earthquake. We report that supershear earthquakes are characterized by a specific pattern of aftershocks: The fault plane itself is remarkably quiet whereas aftershocks cluster off the fault, on secondary structures that are activated by the supershear rupture. The post-earthquake quiescence of the fault shows that friction is relatively uniform over supershear segments, whereas the activation of off-fault structures is explained by the shock wave radiation, which produces high stresses over a wide zone surrounding the fault.
近期研究表明，地震断层可能会以超过岩石剪切波速度的速度破裂。这种超剪切破裂在地面产生一种地震冲击波，类似于超音速飞机产生的音爆。这种冲击波可能会增加地震造成的破坏。我们报告称，超剪切地震具有特定的余震模式：断层面本身异常平静，而余震则聚集在断层之外，位于由超剪切破裂激活的次生构造上。断层震后的静止状态表明，在超剪切段上摩擦力相对均匀，而非断层构造的激活则是由冲击波辐射导致的，冲击波辐射在断层周围的广阔区域产生高应力。
