Detailed imaging of the fault planes of the 2004 Niigata-Chuetsu, central Japan, earthquake sequence by double-difference tomography
Detailed imaging of the fault planes of the 2004 Niigata-Chuetsu, central Japan, earthquake sequence by double-difference tomography
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DOI：
10.1016/j.epsl.2006.02.010
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发表时间：
2006-04-15
影响因子：
5.3
通讯作者：
Thurber, CH
中科院分区：
文献类型：
--
作者：
Okada, T;Yaginuma, T;Thurber, CH
利用在震源区密集部署的临时余震观测网络获得的数据，通过双差层析成像对新泻-中津地震序列的震源断层进行成像。揭示了两个平行的“不利方向”的断层面，它们急剧倾斜于西北西向，即主震断层面和最大余震断层面，以及P波和S波的高速下盘和低速上盘之间的速度变化区。这表明主震和最大余震是由中新世正断层在当前挤压应力状态下重新活动引起的。部分断层面也被发现位于低速区内。这个低速区一直延伸到下地壳，这是通过区域数据反演成像的，并且与断层面周围具有高流体压力的高度断裂带相对应，这重新激活了“不利方向”的断层并引发了当前的地震。较大的同震滑动区似乎以相对较高的速度延伸到东北部。这表明主震的粗糙度（大的同震滑动区域）可能对应于沿断层面的较高速度区域。 (c) 2006 Elsevier B.V. 保留所有权利。
Imaging of the hypocentral faults of the Niigata-Chuctsu earthquake sequence was performed by double-difference tomography using data obtained by a temporary aftershock observation network densely deployed in the hypocentral region. Two parallel "unfavorly oriented" fault planes steeply inclined to the WNW are revealed, that of the main shock and that of the largest aftershock, as well as a zone of velocity change between the high-velocity footwall and the low-velocity hanging wall for both Pand S-waves. This suggests that the main shock and the largest aftershock are caused by the reactivation of normal faults in the Miocene under the current compressional stress regime. Parts of the fault planes are also found to be located within the low-velocity zone. This low-velocity zone continues to the lower crust, which is imaged by an inversion from the regional data, and would correspond with highly fractured zone around the fault plane with high fluid pressure, which reactivated the "unfavorly oriented" fault and triggered the present earthquake. Large coseismic slip area appears to extend to the northeastern portion with relatively high velocity. This Suggests that the asperity (large coseismic slip area) of the main shock possibly correspond with a higher velocity region along the fault plane. (c) 2006 Elsevier B.V. All rights reserved.