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首页> 外文期刊>Journal of Volcanology and Geothermal Research >Focal mechanisms of recent seismicity at Campi Flegrei, Italy
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Focal mechanisms of recent seismicity at Campi Flegrei, Italy

机译：意大利Campi Flegrei最近地震活动的震源机制

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The present study analysed volcano tectonic earthquakes that occurred in the caldera of Campi Flegrei, Italy from 2000 to 2019 to compute source focal mechanisms. We used data from a large number of seismic stations to estimate reliable fault plane solutions for 71 events of a maximum duration magnitude (Mo) ranging between 0.5 <= M-D <= 2.5. We found that most solutions were of a normal type and were rake-angle negative focal mechanisms in 86% of the cases. Only a few earthquakes occurred on normal dip-slip faults; the majority occurred on varying degrees of oblique slip. Only one event had a pure reverse-mechanism, and it was located far from the caldera centre. The spatial distribution of the computed mechanisms exhibited a remarkable mix of fault orientations without any relationship to the location area or source depth. The predominance of normal kinematics on high-angle and nearly vertical faults and the very shallow source depth exhibited good agreement with the fact that seismicity at Campi Flegrei occurred during periods of ground uplift. In fact, ground uplift elongated the shallowest crust, thus reducing the normal stress on existing locked faults; this facilitated earthquakes, particularly those characterised by normal, dip-slip, and strike-slip mechanisms. In contrast, ground subsidence produced a horizontal shortening of the upper crust, which increased the normal stress on high-angle faults and reduced earthquake occurrence. Our results indicate that the driving force of the recent volcano-tectonic seismicity in the study region is the ongoing ground uplift. (C) 2019 Elsevier B.V. All rights reserved.
机译：本研究分析了2000年至2019年意大利Campi Flegrei火山口的火山构造地震，以计算震源机制。我们使用来自大量地震台站的数据来估计71个最大持续时间震级（Mo）在0.5 <= M-D <= 2.5之间的事件的可靠断层平面解。我们发现大多数解决方案属于正常类型，在86％的情况下为前角负焦点机制。正常的倾滑断层只发生了几次地震。大多数发生在不同程度的斜滑。只有一个事件具有纯粹的反向机制，并且它位于远离火山口中心的位置。计算机构的空间分布表现出断层定向的显着混合，与位置区域或震源深度没有任何关系。正常运动学在大角度和近乎垂直的断层上的优势以及很浅的震源深度显示出与Campi Flegrei地震活动发生在地面隆起时期这一事实的良好一致性。实际上，地面隆起拉长了最浅层的地壳，从而降低了现有锁定断层的法向应力。这促进了地震的发生，特别是那些以正常，倾滑和走滑机制为特征的地震。相反，地面沉降使上地壳水平缩短，从而增加了高角度断层的法向应力，减少了地震的发生。我们的结果表明，该研究区最近火山构造地震活动的驱动力是持续的地面隆升。 （C）2019 Elsevier B.V.保留所有权利。

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