Orogen-scale uplift in the central Italian Apennines drives episodic behaviour of earthquake faults.
Orogen-scale uplift in the central Italian Apennines drives episodic behaviour of earthquake faults.
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DOI：
10.1038/srep44858
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发表时间：
2017-03-21
影响因子：
4.6
通讯作者：
Wilkinson M
中科院分区：
文献类型：
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作者：
Cowie PA;Phillips RJ;Roberts GP;McCaffrey K;Zijerveld LJ;Gregory LC;Faure Walker J;Wedmore LN;Dunai TJ;Binnie SA;Freeman SP;Wilcken K;Shanks RP;Huismans RS;Papanikolaou I;Michetti AM;Wilkinson M
地壳的许多地区由于分布的伸展断层和复杂的断层相互作用而变形。大地测量数据通常显示了几十年来连续变形的简单情况，但考虑到许多潜在的活动断层，将这种行为与几个世纪以来的地震发生联系起来，仍然是危害评估中的一个全球性问题。我们为意大利亚平宁山脉中部的一系列发震断层解决了这一挑战，在那里地壳伸展和破坏性地震发生在响应区域表面隆起。我们利用在基岩陡坡上测量的宇宙成因36Cl的变化来约束自~ 18ka以来的断层滑动速率，并使用激光雷达和探地雷达进行测绘，并将这些速率与大地测量推断的速率进行比较。36Cl数据显示，在几千年的时间里，单个断层通常会相对较快地积累数米的位移，当滑动率低得多时，断层之间的活动会发生变化。在较长的时空尺度上（104年，102公里），我们的速率与连续变形速率一致，但在较短的时间尺度上，大多数变形可能被小于30%的跨走向断层阵列所容纳。我们将活动的变化归因于断裂机械功的时间变化。
Many areas of the Earth’s crust deform by distributed extensional faulting and complex fault interactions are often observed. Geodetic data generally indicate a simpler picture of continuum deformation over decades but relating this behaviour to earthquake occurrence over centuries, given numerous potentially active faults, remains a global problem in hazard assessment. We address this challenge for an array of seismogenic faults in the central Italian Apennines, where crustal extension and devastating earthquakes occur in response to regional surface uplift. We constrain fault slip-rates since ~18 ka using variations in cosmogenic 36Cl measured on bedrock scarps, mapped using LiDAR and ground penetrating radar, and compare these rates to those inferred from geodesy. The 36Cl data reveal that individual faults typically accumulate meters of displacement relatively rapidly over several thousand years, separated by similar length time intervals when slip-rates are much lower, and activity shifts between faults across strike. Our rates agree with continuum deformation rates when averaged over long spatial or temporal scales (104 yr; 102 km) but over shorter timescales most of the deformation may be accommodated by <30% of the across-strike fault array. We attribute the shifts in activity to temporal variations in the mechanical work of faulting.