The weakened lower crust beneath the Nobi fault system, Japan: Implications for stress accumulation to the seismogenic zone
The weakened lower crust beneath the Nobi fault system, Japan: Implications for stress accumulation to the seismogenic zone
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日本浓尾断层系下的下地壳减弱：应力积累对发震带的影响
DOI：
10.1016/j.tecto.2015.05.021
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发表时间：
2015
期刊：
影响因子：
2.9
通讯作者：
T. Iwasaki
中科院分区：
文献类型：
--
作者：
J. Nakajima;A. Kato;T. Iwasaki
1891年发生在日本中部诺维断层系沿着的8级诺维地震是日本历史记载中最大的地壳地震。在这里，我们提出了一个新的估计的三维地震速度结构周围的Nobi断层系统使用大量的到达时间数据从临时和永久地震台站。结果表明，Nobi断裂系北方的中、下地壳具有较低的地震速度，比周围地区低4-9%。这个低速地壳很可能代表一个含有2-3体积%降低中下地壳强度的孔隙流体。这一推论表明，在这个弱化的地壳变形，由区域应力制度所造成的东运动和阿穆尔板块与北美板块的碰撞，是由滞弹性过程为主。此外，断层系统北方部分的孕震层比南方部分薄约5 km，这表明应力有效地集中在北方部分的孕震层内。这一发现解释了为什么Nobi地震的地震破裂在断层系统的北方端成核。结果表明，中、下地壳的弱化带是孕震层应力加载过程的重要控制因素，从而对地壳地震的发震起着重要的控制作用。
The 1891 M8 Nobi earthquake, which occurred along the Nobi fault system in central Japan, is the largest crustal earthquake in Japanese historical records. Here, we present a new estimate of the 3-D seismic velocity structures around the Nobi fault system using a large number of arrival time data obtained from both temporary and permanent seismic stations. The results show that the middle and lower crust in the northern part of the Nobi fault system has lower seismic velocities that are 4–9% lower than those of the surrounding area. This low-velocity crust most likely represents a zone containing 2–3 vol.% of pore fluids that reduce the strength of the middle and lower crust. This inference suggests that deformation in this weakened crust, caused by a regional stress regime regulated by the eastward movement and collision of the Amurian plate with the North American plate, is dominated by anelastic processes. In addition, the seismogenic layer in the northern part of the fault system is ~ 5 km thinner than in the southern part, suggesting that stress is efficiently concentrated within the seismogenic layer in the northern part. This finding explains why the seismic rupture for the Nobi earthquake nucleated at the northern end of the fault system. Our results suggest that a weakened zone in the middle and lower crust is an important control on stress loading process within the seismogenic layer and thus the seismogenesis of crustal earthquakes.
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影响因子：
2.9
作者：
Omuralieva, Aiymjan M.;Hasegawa, Akira;Okada, Tomomi
通讯作者：
Okada, Tomomi
影响因子：
3.9
作者：
Nakajima, Junichi;Hirose, Fuyuki;Hasegawa, Akira
通讯作者：
Hasegawa, Akira
影响因子：
3.9
作者：
Nakajima, Junichi;Hasegawa, Akira
通讯作者：
Hasegawa, Akira
影响因子：
5.3
作者：
Nakajima, Junichi;Hasegawa, Akira
通讯作者：
Hasegawa, Akira
DOI：
10.1186/bf03352677
发表时间：
2007-03
期刊：
Earth, Planets and Space
影响因子：
--
作者：
J. Nakajima;A. Hasegawa
通讯作者：
J. Nakajima;A. Hasegawa