Surface deformation and seismicity provide critical information to understand the dynamics of volcanic unrest. During 2006–2007, >80 mm/yr uplift was observed by interferometric synthetic aperture radar (InSAR) at the central Atka volcanic center, Alaska, coinciding with an increasing seismicity rate. On November 25, 2006, a phreatic eruption occurred at the Korovin volcanic vent, 5‐km north of the central Atka, following the drainage of its crater lake a month prior to the eruption. The InSAR data are assimilated into three‐dimensional finite element models using the Ensemble Kalman Filter to investigate: (1) the pressure source creating the surface deformation; (2) the triggering of the volcano‐tectonic (VT) earthquakes in the Atka volcanic center; and (3) the triggering of the phreatic eruption at Korovin. The models show that the pressure source required to create the surface deformation is a NE‐tilted, oblate ellipsoid, which rotated from steep to gentle dipping from June to November 2006 before the eruption. The modeled dilatancy in a pre‐existing weak zone, coinciding with the Amlia‐Amukta fault, driven by the pressure source has a spatial and temporal correlation with the evolution of the VT earthquakes during the unrest. The fault dilatancy may have increased the connected porosity and permeability of the fault zone allowing fluid injection which triggered the observed seismicity. In addition, the dilatated fault may have increased the fluid capacity of the fault zone by ∼10⁵ m³, causing the discharge of the crater lake at Korovin. Consequently, the phreatic eruption of the Korovin volcano may have been triggered.

中文翻译：

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阿拉斯加阿特卡火山中心2006-2007年火山动荡期间岩浆系统演化的模型

地表变形和地震活动性为了解火山动荡的动力学提供了重要信息。在2006-2007年期间，通过干涉合成孔径雷达（InSAR）在阿拉斯加中部阿特卡火山中心观测到> 80 mm / yr的隆起，这与地震活动率不断提高相吻合。2006年11月25日，在喷发前一个月，火山口的湖被排水，在阿特卡中部以北5公里处的科罗温火山喷口发生了一次潜水喷发。使用Ensemble Kalman滤波器将InSAR数据同化为三维有限元模型，以研究：（1）压力源产生表面变形；（2）在阿特卡火山中心引发的火山构造（VT）地震；（3）在Korovin引发潜水爆发。这些模型表明，产生表面变形所需的压力源是NE倾斜的扁椭圆形，从喷发之前的2006年6月至11月，从陡倾变为缓倾。由压力源驱动的，与Amlia-Amukta断层相吻合的既有弱区中的模拟剪胀与动荡期间VT地震的演变具有时空相关性。断层扩张性可能增加了断层带的连通孔隙度和渗透率，允许注入流体触发了观测到的地震活动。此外，膨胀断层可能使断层带的流体容量增加了约10 由压力源驱动的，与Amlia-Amukta断层相吻合的既有弱区中的模拟剪胀与动荡期间VT地震的演变具有时空相关性。断层扩张性可能增加了断层带的连通孔隙度和渗透率，允许注入流体触发了观测到的地震活动。此外，膨胀断层可能使断层带的流体容量增加了约10 由压力源驱动的，与Amlia-Amukta断层相吻合的既有弱区中的模拟剪胀与动荡期间VT地震的演变具有时空相关性。断层扩张性可能增加了断层带的连通孔隙度和渗透率，允许注入流体触发了观测到的地震活动。此外，膨胀断层可能使断层带的流体容量增加了约10 断层扩张性可能增加了断层带的连通孔隙度和渗透率，允许注入流体触发了观测到的地震活动。此外，膨胀断层可能使断层带的流体容量增加了约10 断层扩张性可能增加了断层带的连通孔隙度和渗透率，允许注入流体触发了观测到的地震活动。此外，膨胀断层可能使断层带的流体容量增加了约10⁵  m ³，导致Korovin的火山口湖排放。因此，可能已经引发了科罗温火山的潜水爆发。