Evidence of Low‐Magnitude Continued Reservoir‐Induced Seismicity Associated with the Pertusillo Artificial Lake (Southern Italy)
Evidence of Low‐Magnitude Continued Reservoir‐Induced Seismicity Associated with the Pertusillo Artificial Lake (Southern Italy)
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与佩尔图西洛人工湖（意大利南部）相关的低震级持续水库诱发地震活动的证据
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
L. Telesca
中科院分区：
文献类型：
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作者：
T. Stabile;A. Giocoli;V. Lapenna;A. Perrone;S. Piscitelli;L. Telesca
水库诱发地震活动性（RIS）的最常见观测结果通常与湖泊的初始蓄水或湖泊水位高于先前最大值有关。罕见的是，RIS持续多年而不减少频率或强度；如果发生这种情况，它被称为“持久的”或“持续的”地震活动。位于意大利南部阿格里河谷的Pertusillo人工湖是一个小型水库，水柱平均每年波动约10-15米，对应于湖底的压力扰动为0.10-0.15 MPa。虽然水库在1963年就已蓄水，但湖周围仍有微地震活动，因此可以将此类RIS归类为持续地震活动。我们收集了2005年1月至2012年6月两个不同地震台网记录的水库附近所有微地震（M L≤2.7），并分析了它们的频率-震级分布，结果表明b值（b =1.40）远高于调查区预期值。尽管湖的空间地震活动性在湖的东北和西南呈现出两个明显的集群，但我们发现只有西南地震活动性与水位显著相关。研究结果表明，物理驱动机制是沿东北-西南断裂带连接储层至Monti della Maddalena断裂带南端的一维孔隙流体压力扩散，平均水力扩散系数为~ 7.8 m2/s。
The most common observations of reservoir‐induced seismicity (RIS) by filling artificial lakes are generally associated with the initial impoundment of the lake or the lake level increase above a previous maximum. Rarely, RIS persists for many years without a decrease in frequency or magnitude; if this occurs, it is called “protracted” or “continued” seismicity. Pertusillo artificial lake in high Agri Valley (southern Italy) is a small reservoir with a water column that fluctuates yearly by about 10–15 m (on average), corresponding to a pressure perturbation at the bottom of the lake of 0.10–0.15 MPa. Although the reservoir was filled in 1963, the microearthquake activity still occurring around the lake allows the categorization of such RIS as continued seismicity. We collected all microearthquakes ( M L≤2.7) recorded near the reservoir by two different seismic networks from January 2005 to June 2012 and analyzed their frequency–magnitude distribution, which showed a b value ( b =1.40) much higher than that expected for the investigated area. Even though the spatial seismicity pattern shows two distinct clusters to the northeast and southwest of the lake, we found that only the southwest seismicity is significantly correlated with the water level. The findings suggest that the physical driving mechanism is the 1D pore fluid pressure diffusion along the northeast–southwest fault zones, connecting the reservoir to the southern termination of the Monti della Maddalena fault system, with an average hydraulic diffusivity of ∼7.8 m2/s.
Online Material: Figures of magnitude comparisons between catalogs, temporal occurrence of events, rainfall versus number of earthquakes, and number of events versus water level, and animated 3D views of seismicity and reservoir.