地震-电成像联合探测试验——以淄博市活断层探测为例

EXPERIMENT ON JOINT DETECTION BY SEISMIC REFLECTION AND ELECTRICAL IMAGING:WITH AN EXAMPLE OF EXPLORATION OF ACTIVE FAULT IN ZIBO CITY

在城市浅部活断层探测中,地震和电成像是2种主要的地球物理勘探手段。它们既可独立开展工作,也可在地质构造复杂地段进行联合探测,以更合理地解释探测区域的地质构造。文中利用电阻率和地震纵波速度之间的简单关系,进行了地震-电成像联合反演的初步探索。结果表明,通过参考电成像图像的电阻率分布,可获得合理的准二维地震波叠加速度模型,最终获得探测区域合理的地震时/深剖面,深化对地质构造的认识和提供合理的解释。

In exploration of a shallow active fault in urban area, seismic reflection survey and electrical imaging are the two main geophysical tools. Both of them can be implemented independently. However, the complexity of subsurface geologic tectonics, especially the lateral irregularities close to fault and geologic tectonic zones could result in great deviation from the detected results. In the meantime, the geophysical inversion has not only one result. These would lead to a large difference of stacked veloci- ty model established only by its own information from real one in seismic data processing. In consequence, the geologic interpretation would be harmed. On the other hand, electrical imaging is very sensitive to the lateral irregularities of rock properties but has weak resolution in depth. Therefore, the two techniques can just compensate each other and a joint detection can be carried out to interpret a complex geologic tectonics more reasonably. In this paper, experiment on the joint detection using seismic reflection survey and electrical imaging is made basing on the simple relationship between resistivity and seismic P-wave velocity： Pα∝｜ Z ｜ ^2 ∝ Vp^2. It is shown that a reasonable quasi 2-D seismic stacked velocity model can be obtained referring to the resistivity image from electrical imaging. In the end, the reasonable seismic reflection and time-depth conversion profiles are gotten, which is helpful for further understanding and more reasonably interpreting the geological structures.