Correction to “A persistent localized microseismic source near the Kyushu Island, Japan”
Correction to “A persistent localized microseismic source near the Kyushu Island, Japan”
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DOI：
10.1029/2011gl048822
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发表时间：
2011-08
影响因子：
5.2
通讯作者：
Xiangfang Zeng;S. Ni
中科院分区：
文献类型：
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作者：
Xiangfang Zeng;S. Ni
[1]在Xiangfang Zeng和Sidao Ni的论文“A persistent localized microseismic source near the Kyushu Island，Japan”（Geophysical Research Letters，37，L24307，doi：10.1029/2010 GL 045774）[Zeng and Ni，2010]中，基于环境地震噪声观测之间的互相关性，我们提出了日本九州岛附近存在时间上持续的局部微地震源的证据。由于震源的振幅与季节无关，而且似乎位于九州岛，我们认为它可能是非海洋起源的。我们得出的结论是，来源是有趣的，但神秘的。[2]在我们的论文发表后，H。Kawakatsu（个人通信，2011年）确定了微震能量的可能来源是日本九州的阿索火山。基于对阿索火山的长期研究历史（我们基本上不知道），我们同意他们的评估。位于九州岛中心附近的阿索火山的特点是火山震动，优势周期为3. 5 - 8. 0秒，自20世纪30年代首次探测后一直持续观测到[例如，Sassa，1935;Kubotera，1974]。最近使用宽带地震仪的观测揭示了具有15秒周期的较低模式的存在，这可以解释我们在8秒和14秒周期之间观察到的峰值能量，并且信号的性质和产生机制已经被广泛研究[例如，Kawakatsu等人，1994; Kaneshima等人，1996;Kawakatsu等人，2000; Legrand等人，2000; Yamamoto等人，1999; Kawakatsu和Yamamoto，2007]。[3]由于近场观测的有效性，阿索火山的长周期地震已经得到了很好的研究。我们的研究证明了环境噪声互相关在检测和定位微弱但持久的信号方面的能力，即使是在相对稀疏的远程网络中。例如，1997年8月26日，在中国东部的SSE站，我们没有观测到0.07-0.12Hz波段的长周期震颤信号（图1），尽管九州岛的当地观测在这一天清楚地显示了长周期震颤[Yamamoto et al.，1999，图2a]。因此，长周期震颤在如此大的距离处低于噪声水平，但是可以通过使用环境噪声数据处理的标准方法对环境地震噪声进行互相关来检测[例如，Bensen等人，2007年]。另一方面，表现出持续局部微震效应的互相关必须在用于作为环境噪声层析成像的一部分的色散测量之前对这些信号脱敏（例如，Y. Zheng等人，中国东北、朝鲜半岛和日本海的环境噪声层析成像，提交给《地球物理研究杂志》，2011年，中国东北）。[4]在全球地震网（GSN）目前的覆盖范围内，长时间序列之间的互相关可用于检测已知来源（例如已识别的火山）或未知来源（例如未识别的海底火山或堤坝活动）产生的弱信号（信号噪声水平小于1）例如Shapiro等人对26秒微震的观察。[2006]。当然，近场地球物理观测（如果可用）将为监测与火山系统相关的各种过程提供更好的信息[Yamamoto等人，2007年]。
[1] In the paper “A persistent localized microseismic source near the Kyushu Island, Japan” by Xiangfang Zeng and Sidao Ni (Geophysical Research Letters, 37, L24307, doi:10.1029/2010GL045774) [Zeng and Ni, 2010], based on cross‐correlations between observations of ambient seismic noise, we presented evidence for a temporally persistent localized microseismic source near Kyushu Island, Japan. Because the source’s amplitude does not correlate with seasons and it appears to be located on the island of Kyushu, we proposed that it was probably non‐oceanic in origin. We concluded that the source was interesting but enigmatic. [2] After our paper was published, H. Kawakatsu (personal communication, 2011) identified the likely source of the microseismic energy as Aso volcano, Kyushu, Japan. Based on the long history of studies of Aso volcano (of which we were largely unaware) we concur with their assessment. Aso volcano, which is located near the center of Kyushu Island, is characterized by volcanic tremors with a dominant period of 3.5–8.0 sec, which have been continually observed after the first detection in the 1930s [e.g., Sassa, 1935;Kubotera, 1974]. Recent observations using broadband seismometers revealed the existence of a lower mode with 15 sec period, which may explain the peak energy we observe between periods of 8 and 14 sec, and the nature and generation mechanism of the signal have been extensively studied [e.g., Kawakatsu et al., 1994; Kaneshima et al., 1996;Kawakatsu et al., 2000; Legrand et al., 2000; Yamamoto et al., 1999; Kawakatsu and Yamamoto, 2007]. [3] The long period tremor from Aso volcano has been well studied because of the availability of near field observations. Our study demonstrates the power of ambient noise cross‐correlations to detect and locate weak but persistent signals even with a relatively sparse remote network. For example, at station SSE in eastern China, we did not observe long period tremor signals in the band of 0.07–0.12Hz (Figure 1) on August 26, 1997, a even though local observations on Kyushu Island show long period tremors clearly on this day [Yamamoto et al., 1999, Figure 2a]. The long period tremor, therefore, is below noise level at such large distances, but can be detected by cross‐correlating ambient seismic noise using standard methods of ambient noise data processing [e.g., Bensen et al., 2007]. On the other hand, cross‐ correlations that exhibit the effects of persistent localized microseisms must be desensitized to these signals prior to being used for dispersion measurements as part of ambient noise tomography (e.g., Y. Zheng et al., Ambient noise tomography of northeastern China, the Korean Peninsula, and the Sea of Japan, submitted to Journal of Geophysical Research, 2011, in northeastern China). [4] With the current coverage of Global Seismic Network (GSN), cross‐correlations between long time series can be used to detect weak signals (signal noise level less than 1) generated by sources of known origin (such as identified volcanoes) or unknown sources (such as unidentified‐submarine volcanoes or dyke activities) such as the observation of the 26 sec microseism by Shapiro et al. [2006]. Of course, near field geophysical observations, if available, would provide better information for monitoring various processes associated with the volcanic system [Yamamoto et al., 2007].