At the site of a water drainage shaft on the campus of Qatar University that serves as a man-made karst analog, two seismic imaging techniques were adapted to use resonant scattered waves recorded during active-source seismic surveys and during passive ambient-noise surveys. Data acquisition included two seismic transmission surveys that encompassed the shaft and a passive ambient-noise survey that extended across the top of the shaft. Seismic imaging of band-pass-filtered resonance waves correctly estimated the location and dimension of the shaft. Furthermore, the method detected the presence and the location of a horizontal drainage pipe and gravel bed connecting neighboring water shafts. Ambient-noise data were analyzed by computing amplitude values of the seismic records in spectral passbands. The results indicated an amplification of seismic amplitudes above the shaft for low-frequency passbands and a sharp decrease in amplitude values for high-frequency passbands. The high- and low-amplitude values displayed as a function of the receiver position allowed for accurate detection and location of the shaft in space. Ground truthing of the imaging results confirmed the accuracy of the seismic techniques, whereas numerical modeling supported the interpretation of the ambient-noise data. The techniques used do not require knowledge of the seismic velocities in the subsurface, but they depend on a priori information about the approximate location of the target.

中文翻译：

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人造喀斯特类似物的地震检测与表征—可行性研究

在卡塔尔大学校园的一个排水井作为人造喀斯特模拟物的现场，对两种地震成像技术进行了改造，以利用在主动震源地震勘测和被动环境噪声勘测期间记录的共振散射波。数据采集​​包括两个包含竖井的地震传播调查和一个横跨竖井顶部的被动环境噪声调查。带通滤波后的共振波的地震成像正确估计了轴的位置和尺寸。此外，该方法还检测了水平排水管和连接相邻水井的砾石床的位置。通过计算频谱通带中地震记录的振幅值来分析环境噪声数据。结果表明，对于低频通带，竖井上方的地震振幅有所放大，而对于高频通带，振幅急剧下降。根据接收器位置显示的高振幅值和低振幅值允许在空间中精确检测和定位轴。成像结果的地面实测证实了地震技术的准确性，而数值建模则支持了对环境噪声数据的解释。所使用的技术不需要了解地下的地震速度，但它们取决于有关目标的大致位置的先验信息。根据接收器位置显示的高振幅值和低振幅值允许在空间中精确检测和定位轴。成像结果的地面实测证实了地震技术的准确性，而数值建模则支持了对环境噪声数据的解释。所使用的技术不需要了解地下的地震速度，但它们取决于有关目标的大致位置的先验信息。根据接收器位置显示的高振幅值和低振幅值允许在空间中精确检测和定位轴。成像结果的地面实测证实了地震技术的准确性，而数值模拟则支持了对环境噪声数据的解释。所使用的技术不需要了解地下的地震速度，但它们取决于有关目标的大致位置的先验信息。