Physically Consistent Modeling of Dike‐Induced Deformation and Seismicity: Application to the 2014 Bárðarbunga Dike, Iceland
Physically Consistent Modeling of Dike‐Induced Deformation and Seismicity: Application to the 2014 Bárðarbunga Dike, Iceland
复制标题
堤坝引起的变形和地震活动的物理一致模型：应用于 2014 年冰岛 Bárðarbunga 堤坝
DOI：
--
复制
发表时间：
2019
期刊：
影响因子：
--
通讯作者：
P. Segall
中科院分区：
文献类型：
--
作者：
E. Heimisson;P. Segall
堤坝侵入通常与地表变形和地震群传播有关。这些被理解为同一潜在物理过程的表现，尽管很少如此建模。我们构建了 2014 年 Bárðarbunga 堤坝的物理模型，这是迄今为止观察到的最佳大型堤坝（> 0.5 km 3 ）。我们通过总堤坝变形、来自连续 GPS 的时间相关堤坝压力和地震群的范围以及通过地震活动时空演化的摩擦特性的空间依赖性来约束背景应力状态。我们发现大地测量和地震数据可以通过一组自洽的参数进行协调。 Bárðarbunga 地震活动复杂的时空演化可以通过岩脉引起的现有断层上的弹性应力变化来解释，并受到观测到的震源机制的约束。特别是，该模型捕获了地震活动的分段，其中只有最新的岩脉段是地震活跃的。我们的结果表明，地震活动的许多特征是由岩脉内随时间变化的岩浆压力与应力记忆效应之间的相互作用造成的。地震活动的空间变化需要摩擦特性和/或局部初始应力的异质性。建模表明，堤坝压力在快速前进期间下降，在暂停期间增加，这主要导致地震活动的分割。多种数据类型的联合分析可能会改进基于物理的喷发预测。
Dike intrusions are often associated with surface deformation and propagating swarms of earthquakes. These are understood to be manifestations of the same underlying physical process, although rarely modeled as such. We construct a physics‐based model of the 2014 Bárðarbunga dike, by far the best observed large dike ( > 0.5 km 3 ) to date. We constrain the background stress state by the total dike deformation, the time‐dependent dike pressure from continuous GPS and the extent of the seismic swarm, and the spatial dependence of frictional properties via the space‐time evolution of seismicity. We find that the geodetic and earthquake data can be reconciled with a self‐consistent set of parameters. The complex spatial and temporal evolution of the Bárðarbunga seismicity can be explained by dike‐induced elastic stress changes on preexisting faults, constrained by observed focal mechanisms. In particular, the model captures the segmentation of seismicity, where only the newest dike segment is seismically active. Our results indicate that many features of the seismicity result from the interplay between time‐dependent magma pressure within the dike and stress memory effects. The spatial variability in seismicity requires heterogeneity in frictional properties and/or local initial stresses. Modeling suggests that the dike pressure drops during rapid advances and increases during pauses, which primarily causes the segmentation of the seismicity. Joint analysis of multiple data types could potentially lead to improved, physics‐based eruption forecasts.