Ridge subduction and afterslip control aftershock distribution of the 2016 Mw 7.8 Ecuador earthquake
Ridge subduction and afterslip control aftershock distribution of the 2016 Mw 7.8 Ecuador earthquake
复制标题
2016年厄瓜多尔7.8级地震的山脊俯冲与后滑控制余震分布
DOI：
10.1016/j.epsl.2019.05.029
复制
发表时间：
2019
影响因子：
5.3
通讯作者：
Courboulex, F.
中科院分区：
文献类型：
--
作者：
Agurto-Detzel, H.;Font, Y.;Charvis, P.;Régnier, M.;Rietbrock, A.;Ambrois, D.;Paulatto, M.;Alvarado, A.;Beck, S.;Courboulex, F.
我们对2016年Pedernales足目7.8级地震后的余震序列进行了分析。探测和定位了超过10，000次事件，震级高达6.9级。大多数余震地震活动的结果板间逆冲断层，但我们也观察到一些正常和走滑机制。地震活动沿走向延伸沿着300 km以上，并被限制在海沟和同震破裂的最大深度之间。最显著的特征是存在三个垂直于海沟的地震活动带，这也是在地震间隔期间观察到的。此外，我们观察到的线性关系之间的时间演化的余震和余震。我们还发现，余震地震活动的时间半对数扩展沿着走向和倾向的方向，进一步表明，他们的发生调制后滑。最后，我们观察到，地震和地震滑动过程的空间分布与卡内基海岭的北方翼相关的测深异常的分布，这表明该地区的滑动可能会受到俯冲海底的救济。为了解释我们的观测结果，我们提出了一个概念模型，在该模型中，厄瓜多尔的边缘受到双峰滑动模式，分布地震和地震滑动机械控制的俯冲粗糙的海洋救济。我们的研究揭示了新的俯冲机制，相关的收敛边缘的复杂和异质结构，如厄瓜多尔的边缘。
We characterise the aftershock sequence following the 2016 Mw = 7.8 Pedernales earthquake. More than 10,000 events were detected and located, with magnitudes up to 6.9. Most of the aftershock seismicity results from interplate thrust faulting, but we also observe a few normal and strike-slip mechanisms. Seismicity extends for more than 300 km along strike, and is constrained between the trench and the maximum depth of the coseismic rupture. The most striking feature is the presence of three seismicity bands, perpendicular to the trench, which are also observed during the interseismic period. Additionally, we observe a linear dependency between the temporal evolution of afterslip and aftershocks. We also find a temporal semi-logarithmic expansion of aftershock seismicity along strike and dip directions, further indicating that their occurrence is modulated by afterslip. Lastly, we observe that the spatial distribution of seismic and aseismic slip processes is correlated to the distribution of bathymetric anomalies associated with the northern flank of the Carnegie Ridge, suggesting that slip in the area could be influenced by the relief of the subducting seafloor. To explain our observations, we propose a conceptual model in which the Ecuadorian margin is subject to a bimodal slip mode, with distributed seismic and aseismic slip mechanically controlled by the subduction of a rough oceanic relief. Our study sheds new light on the mechanics of subduction, relevant for convergent margins with a complex and heterogeneous structure such as the Ecuadorian margin.