Attenuation structure of Coso geothermal area, California, from wave pulse widths
Attenuation structure of Coso geothermal area, California, from wave pulse widths
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加利福尼亚州科索地热区波脉冲宽度的衰减结构
DOI：
10.1785/bssa0860051574
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发表时间：
1996
影响因子：
3
通讯作者：
J. Lees
中科院分区：
文献类型：
--
作者：
Huatao Wu;J. Lees
利用脉宽数据对加利福尼亚州COSO地热区的衰减结构进行了反演。该数据集包括1993年8月至1994年3月在16个井下台站的地震台阵上记录的838个微震事件的脉冲宽度测量。品质因数Q与地表地质和地表热流观测有很好的相关性。一大片低Q(≈30到37)的区域位于魔鬼厨房、尼科尔前景和科索温泉下方0.5至1.2千米深。垂直的低Q区(≈为36，而围岩为80)被解释为热液能量从深部输送到地表的通道。该通道位于S1和S4站之间，其尺寸约为1公里。在海峡的深端，尼科尔前景和魔鬼厨房西南方向2至4公里处也有一个巨大而宽广的低Q天体。由于它位于目标区域的底部，超出了地震活动的范围，因此需要进一步的研究来限制其范围。用伪谱方法进行了数值模拟，研究了该反演方法对裂隙地区的适用性。建立了脉宽展宽与行程时间之间的线性关系，并估算了比例常数。
Pulse width data are used to invert for attenuation structure in the Coso geothermal area, California. The dataset consists of pulse width measurements of 838 microseismic events recorded on a seismic array of 16 downhole stations between August 1993 and March 1994. The quality factor Q correlates well with surface geology and surface heat flow observations. A broad region of low Q (≈ 30 to 37) is located at 0.5 to 1.2 km in depth below Devil's Kitchen, Nicol Prospects, and Coso Hot Springs. A vertical, low Q (≈ 36 in contrast with surrounding rock of 80) region is interpreted as a channel through which hydrothermal energy is transported from depth to the surface. The location of the channel is between stations S1 and S4, and its dimension is about 1 km. At the deep end of the channel, a large, broad body of low Q is also located at 3 km in depth 2 to 4 km to the southwest of Nicol Prospects and Devil's Kitchen. Since it lies at the bottom of the target region and beyond the scope of seismicity, further research is needed to constrain its extent. Numerical modeling with a pseudospectral method is also done to investigate the applicability of the inversion scheme to fractured regions. A linear relationship between pulse width broadening and travel time is upheld, and the proportional constants are estimated.