Ambient seismic noise is caused by a number of sources in specific frequency bands. The quantification of ambient noise makes it possible to evaluate station and network performance. We evaluate noise levels in Norway from the 2013 data set of the Norwegian National Seismic Network as well as two temporary deployments. Apart from the station performance, we studied the geographical and temporal variations, and developed a local noise model for Norway. The microseism peaks related to the ocean are significant in Norway. We, therefore, investigated the relationship between oceanic weather conditions and noise levels. We find a correlation of low-frequency noise (0.125–0.25 Hz) with wave heights up to 900 km offshore. High (2–10 Hz) and intermediate (0.5–5 Hz) frequency noise correlates only up to 450 km offshore with wave heights. From a geographic perspective, stations in southern Norway show lower noise levels for low frequencies due to a larger distance to the dominant noise sources in the North Atlantic. Finally, we studied the influence of high-frequency noise levels on earthquake detectability and found that a noise level increase of 10 dB decreases the detectability by 0.5 magnitude units. This method provides a practical way to consider noise variations in detection maps.

中文翻译：

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挪威的环境噪声水平和检测阈值。

环境地震噪声是由特定频段中的多个源引起的。环境噪声的量化使评估站点和网络性能成为可能。我们根据挪威国家地震台网的2013年数据集以及两个临时部署评估了挪威的噪声水平。除了台站性能外，我们还研究了地理和时间变化，并为挪威开发了本地噪声模型。与海洋有关的微地震峰在挪威很重要。因此，我们研究了海洋天气状况与噪声水平之间的关系。我们发现低频噪声（0.125–0.25 Hz）与近海波高达900 km的相关性。高（2–10 Hz）和中（0.5–5 Hz）频率的噪声仅与波高相距不超过450 km。从地理角度来看，由于与北大西洋主要噪声源的距离较大，挪威南部的电台显示出较低的低频噪声水平。最后，我们研究了高频噪声水平对地震可检测性的影响，发现噪声水平增加10 dB会使可检测性降低0.5个数量级单位。该方法提供了一种考虑检测图中噪声变化的实用方法。