Morabito Simona, Cusano Paola, Nardone Lucia, Petrosino Simona
Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Napoli - "Osservatorio Vesuviano", 80124, Naples, Italy.
Sci Rep. 2024 Aug 22;14(1):19480. doi: 10.1038/s41598-024-70022-4.
In the Summer 2021 a seismic passive survey was carried out at Mefite d'Ansanto (Italy), well-known for the cold non-volcanic and lethal CO emissions. Mefite is located close to that part of Irpinia region hosting the large historical earthquakes' faults, that generated the destructive magnitude 6.8 earthquake of 1980 and have been related to the CO leakage by the scientific community. The survey was conducted by installing a small short-period seismic array with the purpose of determining the wavefield features and detecting the possible signature of the regional stress variations. By analyzing the acquired data, we have determined the properties of the seismic wavefield associated with the emission vents, in the intermediate frequency band, 1-15 Hz, which was found to be composed of a stationary background component and an intermittent higher energy one. Basing on our results, considerations on the medium properties and the deep source available information, we have depicted a schematic model of the shallow seismic source: the background components are linked to the shallower activity of the hydrothermal system, e.g. the bubbling, while the intermittent ones are likely generated by the passage of the overpressured gas, trapped in the first-tens-meters' layers, after overcoming the internal cohesion charge. The characteristics of the wavefield that we have defined, refer to a condition in which no regional earthquakes occurred and could be considered as a basis to identify possible significant variations linked to CO emissions and to the regional stress changes.
2021年夏季，在意大利安桑托的梅菲泰进行了一次地震被动监测，该地以低温非火山性且致命的一氧化碳排放而闻名。梅菲泰位于伊尔皮尼亚地区靠近大型历史地震断层的部分，这些断层引发了1980年6.8级的破坏性地震，科学界认为其与一氧化碳泄漏有关。此次监测通过安装一个小型短周期地震阵列来进行，目的是确定波场特征并检测区域应力变化的可能信号。通过分析采集到的数据，我们确定了与排放口相关的地震波场在1 - 15赫兹中频带的特性，发现其由一个稳定的背景分量和一个间歇性的高能分量组成。基于我们的结果，结合介质特性和深部源的可用信息，我们描绘了一个浅部地震源的示意模型：背景分量与热液系统较浅部的活动有关，例如冒泡，而间歇性分量可能是由被困在最初几十米地层中的超压气体在克服内部内聚电荷后通过而产生的。我们所定义的波场特征，指的是未发生区域地震的一种情况，可被视为识别与一氧化碳排放和区域应力变化相关的可能显著变化的基础。
