Seismic Noise in Central Alaska and Influences From Rivers, Wind, and Sedimentary Basins
Seismic Noise in Central Alaska and Influences From Rivers, Wind, and Sedimentary Basins
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阿拉斯加中部的地震噪声以及河流、风和沉积盆地的影响
DOI：
10.1029/2019jb017695
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
C. Tape
中科院分区：
文献类型：
--
作者：
Kyle Smith;C. Tape
环境噪声对于表征频率相关噪声水平和评估地震台站的数据质量非常有用。我们使用4年的环境噪声谱从16个站在阿拉斯加中部的地震台站研究环境和结构的影响。该地区有一条主要河流（塔纳纳河），每年有半年被冰雪覆盖，下面是一个沉积盆地（Nenana盆地），对地震波场有很大影响。Nenana盆地在0.1-0.7 Hz时将环境地震噪声放大12-16 dB，在0.7-3 Hz时将环境地震噪声放大17-30 dB。Nenana的一个气象站和河流测量仪提供了环境数据，可与地震站进行比较。在夏季，塔纳纳河产生的噪音水平升高了30-40分贝，频率接近10赫兹，在100米的主要河道内的所有五个站记录。塔纳纳河沉积物在该地区主要是粉砂和沙子;因此，我们将10-Hz河流信号归因于水中的湍流和河底的不稳定剪切。风对地震噪声的影响在低频率（<0.05 Hz）下是明显的，这是由于大气引起的倾斜，在高频率（>2.0 Hz）下是由于地面附近的不稳定剪切和湍流。我们的实证研究结果激发了未来的研究，例如空气或水的流动如何耦合到地面，以及深沉积盆地如何影响环境噪声波场。我们的研究结果对地震选址，环境监测，地震的检测和表征具有一定的意义。
Ambient noise is useful for characterizing frequency‐dependent noise levels and for assessing data quality for seismic stations. We use 4 years of ambient noise spectra from 16 stations in central Alaska to examine environmental and structural influences on seismic stations. The region contains a major river (Tanana River) that is ice covered for half the year and is underlain by a sedimentary basin (Nenana basin) that strongly influences the seismic wavefield. Nenana basin amplifies ambient seismic noise by 12–16 dB at 0.1–0.7 Hz and 17–30 dB at 0.7–3 Hz. A meteorological station and river gauge at Nenana provide environmental data for comparison with seismic stations. During the summer, the Tanana River produces noise levels elevated by 30–40 dB at frequencies near 10 Hz, as recorded by all five stations within 100 m of the main river channel. The Tanana River sediment is predominantly silt and sand in this region; therefore, we attribute the 10‐Hz river signal to turbulence within the water and to unsteady shearing on the river bottom. The influence of wind is apparent on seismic noise at low (<0.05 Hz) frequencies, due to atmospheric‐induced tilting, and at high (>2.0 Hz) frequencies, due to unsteady shearing and turbulence near the ground. Our empirical findings motivate future studies, such as how flow from air or water couples to the ground and how deep sedimentary basins influence the ambient noise wavefield. Our results have implications for seismic site selection, environmental monitoring, and detection and characterization of earthquakes.
影响因子：
18.3
作者：
C. Tape;S. Holtkamp;V. Silwal;J. Hawthorne;Y. Kaneko;J. Ampuero;C. Ji;N. Ruppert;Kyle Smith;M. West
通讯作者：
C. Tape;S. Holtkamp;V. Silwal;J. Hawthorne;Y. Kaneko;J. Ampuero;C. Ji;N. Ruppert;Kyle Smith;M. West
影响因子：
2.8
作者：
Gebauer;Kroner
通讯作者：
Kroner