Energetics of normal earthquakes on dip-slip faults
Energetics of normal earthquakes on dip-slip faults
复制标题
倾滑断层上正常地震的能量
DOI：
--
复制
发表时间：
2012
期刊：
影响因子：
--
通讯作者：
J. Rowland
中科院分区：
文献类型：
--
作者：
D. Dempsey;S. Ellis;R. Archer;J. Rowland
人们普遍认为，地震释放了大量的能量；然而，最常见的组成部分--辐射地震能量--对总能量收支的贡献很小。地震的弹性回弹模型认识到，弹性应变能确实能使地壳移动、变形和加速，并引起摩擦加热。本文提出了伸展构造体制下倾滑断裂破裂的能量收支。一个含有单个断层的弹塑性粘性地壳的计算模型，被模拟为两个摩擦接触的表面，展示了上盘和下盘断块之间相反的能量流动。我们的分析表明，在地震前的一段时间里，地壳内包含的总应变能减少，尽管在地壳中层观察到底部的局部增加。地震时，下盘会发生弹性回弹，断层陡坎的抬升是由中地壳应力降和释放应变能的弹性膨胀引起的。相比之下，从下沉的上盘释放的重力势能确实压缩了更广泛的地壳，特别是在断层尖端的中地壳。这产生了一个不同寻常的后果，即在地震期间，上地壳大部分地区的应变能都会增加。这些反直觉的能量流动表明，伸展变形是由储存的引力势和弹性应变能引起的，而不是由外部构造强迫引起的。
That earthquakes release vast quantities of energy is widely accepted; however, the most commonly experienced component, radiated seismic energy, is a minor contribution to the total energy budget. The elastic rebound model for earthquakes recognizes that elastic strain energy does work displacing, deforming, and accelerating the crust, as well as causing frictional heating. In this paper we present an energy budget for dip-slip fault rupture in an extensional tectonic regime. A computational model of an elastic-plastic-viscous crust hosting a single fault, modeled as two surfaces in frictional contact, demonstrates contrasting energy flows between the hanging-wall and footwall fault blocks. Our analysis suggests that in the period leading up to an earthquake, the total strain energy contained within the crust decreases, although a local increase within the footwall at mid-crustal depths is observed. During an earthquake, the footwall is subject to an elastic rebound, whereupon uplift of the fault scarp is caused by a mid-crustal stress drop and elastic expansion that releases strain energy. In contrast, gravitational potential energy released from a subsiding hanging wall does work compressing the wider crust, particularly in the mid-crust at the fault tip. This has the unusual consequence of increasing strain energy throughout much of the upper crust during an earthquake. These counterintuitive energy flows suggest that extensional deformation is caused by stored gravitational potential and elastic strain energy, and not by the external tectonic forcing.
正断层地震周期中复杂的应力状态：中地壳震后蠕变的作用
影响因子：
--
作者：
Nüchter
通讯作者：
Nüchter