Surface rupture of the 2005 Kashmir, Pakistan, earthquake and its active tectonic implications
Surface rupture of the 2005 Kashmir, Pakistan, earthquake and its active tectonic implications
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DOI：
10.1785/0120070073
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发表时间：
2008-04-01
影响因子：
3
通讯作者：
Kausar, Allah B.
中科院分区：
文献类型：
--
作者：
Kaneda, Heitaro;Nakata, Takashi;Kausar, Allah B.
为了提供一个相对罕见的逆冲表面破裂的详细记录，并检查其积极的构造影响，我们进行了现场测绘的表面破裂与2005年M-W 7.6克什米尔地震。尽管大规模地震引起的滑坡沿着地表破裂带来了困难，但我们发现，典型的压力脊和翘曲向西北方向延伸了大约70 km的距离，东北侧向上的垂直间隔高达大约7 m。无论是主前锋逆冲断层还是主边界逆冲断层都不是地震的原因，而是喜马拉雅山下的三个活动断层或断层段，统称为Balakot-Bagh断层，构成了发震断层。虽然该断层在地貌上表现出重复的类似地表破裂，但在地震前只有一部分被绘制为活动断层。震源的位置表明，破裂是在北部-中部段边界的深部开始的，并向两侧传播，最终打破了所有三个段。我们得到的地表破裂痕迹和沿走滑分布都与卫星图像的即时分析结果吻合得很好，表明空间大地测量可以大大有助于耗时的地表破裂现场制图。假设广泛的填充阶地在极震区被遗弃在10 - 30万年，我们初步估计的地震复发间隔和缩短率的Balakot-Bagh故障为1000-3300年和1：4-4：1毫米/年，分别。这些估计表明，巴拉科特-巴格断层不是喜马拉雅收缩调节的主要参与者。选定的实地照片和地图表面破裂痕迹和测量的垂直分离的ArcGIS文件可在BSSA的电子版。
To provide a detailed record of a relatively rare thrust surface rupture and examine its active tectonic implications, we have conducted field mapping of the surface rupture associated with the 2005 M-w 7.6 Kashmir earthquake. Despite the difficulty arising from massive earthquake-induced landslides along the surface rupture, we found that typical pressure ridges and warps extend northwestward for a distance of similar to 70 km, with a northeast-side-up vertical separation of up to similar to 7 m. Neither the main frontal thrust nor the main boundary thrust is responsible for the earthquake, but three active faults or fault segments within the Sub-Himalaya, collectively called the Balakot-Bagh fault, compose the causative fault. Although the fault exhibits substantial geomorphic expression of repeated similar surface ruptures, only a part of it had been mapped as active before the earthquake. The location of the hypocenter suggests that the rupture was initiated at a deep portion of the northern-central segment boundary and propagated bilaterally to eventually break all three segments. Our obtained surface rupture traces and the along-strike-slip distribution are both in good agreement with results of prompt analyses of satellite images, indicating that space geodesy can greatly aid in time-consuming field mapping of surface ruptures. Assuming that the extensive fill terrace in the meizoseismal area was abandoned during 10 30 ka, we tentatively estimate the earthquake recurrence interval and shortening rate on the Balakot-Bagh fault to be 1000-3300 yr and 1:4-4:1 mm/yr, respectively. These estimates indicate that the Balakot-Bagh fault is not a main player of Himalayan contraction accommodation.. Selected field photographs and ArcGIS files of the mapped surface rupture traces and measured vertical separations are available in the electronic edition of BSSA.