Independent Researcher, Str. Luisetti 12, 10040 Cumiana, Italy.
Independent Researcher, 10053 Bussoleno, Italy.
Sensors (Basel). 2023 Feb 21;23(5):2379. doi: 10.3390/s23052379.
Electromagnetic emissions from earthquakes are known as precursors and are of considerable importance for the purpose of early alarms. The propagation of low-frequency waves is favored, and the range between tens of mHz to tens of Hz has been heavily investigated in the last thirty years. This work describes the self-financed Opera 2015 project that initially consisted of six monitoring stations over Italy, equipped with electric and magnetic field sensors, among others. Insight of the designed antennas and low-noise electronic amplifiers provides both characterization of performance (similar to the best commercial products) and the elements to replicate the design for our own independent studies. Measured signals through data acquisition systems were then processed for spectral analysis and are available on the Opera 2015 website. Data provided by other world-known research institutes have also been considered for comparison. The work provides examples of processing methods and results representation, identifying many exogenous noise contributions of natural or human-made origin. The study of the results occurred for some years and led us to think that reliable precursors are confined to a short area around the earthquake due to the significant attenuation and the effect of overlapping noise sources. To this aim, a magnitude-distance indicator was developed to classify the detectability of the EQ events observed during 2015 and compared this with some other known earthquake events documented in the scientific literature.
地震的电磁辐射被称为前兆，对于早期警报具有重要意义。低频波的传播受到青睐，在过去三十年中，已经对几十毫赫兹到几十赫兹之间的范围进行了大量研究。这项工作描述了 Opera 2015 项目，该项目最初由六个监测站组成，分布在意大利，配备了电场和磁场传感器等设备。设计天线和低噪声电子放大器的深入了解提供了性能的特征化（类似于最佳商业产品）以及复制设计的要素，以便进行我们自己的独立研究。然后，通过数据采集系统测量的信号进行了频谱分析，并在 Opera 2015 网站上提供。还考虑了其他世界知名研究机构提供的数据进行比较。该工作提供了处理方法和结果表示的示例，确定了许多源自自然或人为的外源噪声的贡献。这项研究进行了几年，使我们认为由于显著衰减和重叠噪声源的影响，可靠的前兆局限于地震周围的一个小区域。为此，开发了一个震级-距离指标来对 2015 年观测到的 EQ 事件的可检测性进行分类，并将其与科学文献中记录的一些其他已知地震事件进行了比较。
