Improving the ability to detect and characterize long-duration volcanic tremor is crucial to understand the long-term dynamics and unrest of volcanic systems. We have applied data reduction methods (permutation entropy and polarization degree, among others) to characterize the seismic wave field near Copahue volcano (Southern Andes) between June 2012 and January 2013, when phreatomagmatic episodes occurred. During the selected period, a total of 52 long-duration events with energy above the background occurred. Among them, 32 were classified as volcanic tremors and the remaining as noise bursts. Characterizing each event by averaging its reduced parameters, allowed us to study the range of variability of the different events types. We found that, compared to noise burst, tremors have lower permutation entropies and higher dominant polarization degrees. This characterization is a suitable tool for detecting long-duration volcanic tremors in the ambient seismic wave field, even if the SNR is low.

中文翻译：

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关于火山震颤特征的数据简化方法：2012 年南安第斯山脉 Copahue 火山的喷发

提高检测和表征长期火山震颤的能力对于了解火山系统的长期动态和动荡至关重要。我们应用数据简化方法（排列熵和极化度等）来表征 2012 年 6 月至 2013 年 1 月期间发生潜水岩浆事件的 Copahue 火山（南安第斯山脉）附近的地震波场。在选定的时间段内，总共发生了 52 个能量高于背景的长持续时间事件。其中，32次被归类为火山震颤，其余被归类为噪音爆发。通过平均每个事件的减少参数来表征每个事件，使我们能够研究不同事件类型的可变性范围。我们发现，与噪音爆发相比，震颤具有较低的置换熵和较高的主导极化度。即使 SNR 很低，这种表征也是检测环境地震波场中长期火山震颤的合适工具。