【摘要】 利用由149个台站记录的中国地震年报、四川和云南区域地震台网观测报告的5897个近震的27530条横波振幅与周期资料,反演得到川滇地区及周边的地壳衰减Q0值(频率为1Hz时的Q值)空间分布图像、台站的场地响应以及由于介质衰减不同造成的震级偏差.结果表明,川滇及周边地区的地壳横波衰减Q0值在200~600范围内变化,平均值为400,横向变化显著.在川西-滇西北-保山地区、云贵交界-昆明-思茅地区以及海原-祁连、汾渭和东昆仑等活动块体边界带的Q0值明显较低,这些地区地震和构造活动相对活跃;而构造相对稳定的四川盆地、马尔康块体、桂西滇东断块以及鄂尔多斯、秦岭-大别等地区的Q0值则明显较高.此外,川滇地区大多数台站的场地响应都在1附近,仅有少数增益或衰减较大,达到2倍左右,且其分布无明显规律性.该区观测报告给出的大多数地震震级偏差不大于0.3,但也有少数震级偏差达0.4,其分布与介质品质因子Q0值分布相关,说明震级测定可能受地壳介质衰减横向变化的影响.更多还原

【Abstract】 We have selected 27530 M_L amplitude readings from 5897 events recorded by 149 stations, as reported in the Annual Bulletin of Chinese Earthquakes （ABCE） and regional seismic network of Yunnan province and Sichuan province, and have used tomographic imaging to estimate the lateral variations of the quality factor Q₀ （Q at 1 Hz） in the crust of Sichuan-Yunnan and its adjacent regions. Estimated Q₀ values vary from 200 to 600 with an average of 400. Q₀ values are consistent with tectonic and topographic structure. Q₀ is low in the active tectonic regions having many faults, such as the Haiyuan-Qilian, Fenhe-Weihe, East Kunlun zones, Western Sichuan-Northwestern Yunnan-Baoshan area and joint of Yunnan and Guizhou-Kunming-Simao area. Q₀ is high in the stable regions, such as Sichuan Basin, Markam block, Western Guangxi-Eastern Yunnan block, Ordos Craton and Qinling-Dabie area. Additionally, The gains of most of the station terms in Sichuan-Yunnan and its adjacent regions are near 1.0, only a few as large as 2.0, and the distribution is irregular. Most of the magnitude biases are less than 0.3, only a few as large as 0.4, and the distribution has relation with the Q₀ values distribution, which means that the crustal attenuation has influence on the magnitude measurement.更多还原