刘森,边银菊,王婷婷,鲁志楠. 2021. 云南地区Lg波衰减成像研究. 地震学报,43(4):410−426. doi: 10.11939/jass.20200101
引用本文: 刘森,边银菊,王婷婷,鲁志楠. 2021. 云南地区Lg波衰减成像研究. 地震学报,43(4):410−426. doi: 10.11939/jass.20200101
Liu S,Bian Y J,Wang T T,Lu Z N. 2021. Study on Lg wave attenuation imaging in Yunnan. Acta Seismologica Sinica43(4):410−426. doi: 10.11939/jass.20200101
Citation: Liu S,Bian Y J,Wang T T,Lu Z N. 2021. Study on Lg wave attenuation imaging in Yunnan. Acta Seismologica Sinica43(4):410−426. doi: 10.11939/jass.20200101

云南地区Lg波衰减成像研究

Study on Lg wave attenuation imaging in Yunnan

  • 摘要: 收集了云南省及周边121个固定台站于2014年5月—2019年5月记录到的470次M≥4.0宽频带地震记录,利用反双台法处理了6 976条垂直向波形数据,通过LSQR方法反演得到了云南地区的空间分辨率小于100 km的1 Hz下Lg波衰减成像。反演结果表明,云南地区地壳Lg波的Q0值介于60—300,整体为低Q0背景,横向不均匀性变化显著。云南地区低Q0值的分布特点,反映了Lg波在云南地区衰减强烈。红河断裂西侧Q0值较低,在50—160之间,东侧Q0值较高,在120—200之间,分布特征与沉积层厚度分布一致,松散的沉积层可能是造成东侧地区Lg波高衰减的主要原因。云南地区地壳Lg波Q0值呈现出了与地表热流值分布相似的差异化分布特征,这可能与频繁的地震、长期强烈的构造运动以及深部物质随火山活动上涌有关。

     

    Abstract: In this paper, 470 broadband seismic records of natural earthquakes with M≥4.0 between May 2014 and May 2019 recorded by 121 fixed stations in and around Yunnan Province are collected. 6 976 high-quality vertical wave data is processed by using the reverse two-station method. The attenuation imaging of Lg wave at 1 Hz with spatial resolution less than 100 km in Yunnan area is inverted. The inversion results show that the Q0 value of Lg wave in Yunnan is in 60 to 300 range, and the whole is in low Q0 background, with significant changes in lateral heterogeneity. The distribution characteristics of low Q0 value in Yunnan area reflect the strong attenuation of Lg wave in Yunnan area. The Q0 value in the west side of Honghe fault is relatively low, in 50 to 160 range, and in the east side is relatively high, in 120 to 200 range. The distribution characteristics are consistent with the distribution of sedimentary layer thickness. Loose sedimentary layer may be the main cause of high attenuation in the east side. The Q0 value of Lg wave in Yunnan area shows a similar differential distribution with the distribution of surface heat flow, which may be related to frequent earthquakes, long-term strong tectonic movement and deep material upwelling with volcanic activity.

     

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