Sources of Long-Range Anthropogenic Noise in Southern California and Implications for Tectonic Tremor Detection
Sources of Long-Range Anthropogenic Noise in Southern California and Implications for Tectonic Tremor Detection
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DOI：
10.1785/0120180130
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发表时间：
2018-12-01
影响因子：
3
通讯作者：
Hough, Susan E.
中科院分区：
文献类型：
--
作者：
Inbal, Asaf;Cristea-Platon, Tudor;Hough, Susan E.
我们研究了沿着圣哈辛托断层靠近安扎，南加州的中央部分的地震记录上看到的人为噪声源。最强的信号是由经过安扎北部科切拉山谷的货运列车引起的。列车引起的瞬变观测距离达50公里的铁路，持续时间长达20分钟，和频谱之间的峰值为3和5赫兹。此外，通过科切拉山谷的卡车交通产生持续的嗡嗡声，其光谱特征与火车瞬态相似，但振幅较低。我们还发现，下加利福尼亚北方的风力涡轮机活动会在整个Anza网络中引入1至5 Hz能量的季节性调制。我们表明，所观察到的列车产生的瞬态可以用来约束浅衰减结构在安扎。使用本研究的结果以及可用的钻孔数据，我们进一步评估的方法，已被用来检测在安扎非火山震颤的性能。我们的结论是，以前被确定为自发性震颤的信号（Hutchison和Ghosh，2017）可能是由其他非构造来源（如火车）产生的。
We study anthropogenic noise sources seen on seismic recordings along the central section of the San Jacinto fault near Anza, southern California. The strongest signals are caused by freight trains passing through the Coachella Valley north of Anza. Train-induced transients are observed at distances of up to 50 km from the railway, with durations of up to 20 min, and spectra that are peaked between 3 and 5 Hz. Additionally, truck traffic through the Coachella Valley generates a sustained hum with a similar spectral signature as the train transients but with lower amplitude. We also find that wind turbine activity in northern Baja California introduces a seasonal modulation of 1- to 5-Hz energy across the Anza network. We show that the observed train-generated transients can be used to constrain shallow attenuation structure at Anza. Using the results from this study as well as available borehole data, we further evaluate the performance of approaches that have been used to detect nonvolcanic tremor at Anza. We conclude that signals previously identified as spontaneous tremor (Hutchison and Ghosh, 2017) were probably generated by other nontectonic sources such as trains.