城市断层参数反演的重力异常多尺度边缘方法研究

It is significant to research urban faults，the leading cause to induce urban earthquake, for urban development planning and social sustainable development. As the city is expanding with dense buildings and people, the ordinary methods to research urban faults, such as artificial seismic exploration, electrical exploration and ground penetrating radar, are not convenient to be carried out in urban area due to complex construction scheme and high cost. Gravity measurement becomes an important technology for urban faults in the world, recently. Compared with others, the measurement is economical and efficient. In addition, the gravity inversion，combining with wavelet multi-scale analysis, is advantageous on gravity anomaly extraction, vertical resolution and noise depression. Therefore, a novel multi-scale edge method from gravity anomaly to invert fault parameters is proposed. Based on constructing a non-linear relationship between fault parameters and the multi-scale edge of gravity anomaly, we determine the fault type and location, and invert the fault density and geometrical parameters. And then, the main fault parameters in Shenzhen City are inverted by our method. The achievements in the project can not only be applied for fault researches but also provide a new approach for other relative geophysical inversion.

城市断层是诱发城市地震的首要“元凶”，其研究对城市建设的合理规划和社会的可持续发展具有重要意义。随着城市规模的不断扩大，建筑物和人口越来越密集，当前研究城市断层的常用方法，如人工地震勘探、电法勘探、地质雷达等，施工越来越复杂、成本越来越高。重力测量是国际上近年来兴起的研究城市断层的技术，相比其他方法而言，其数据获取手段经济、高效。除此之外，联合小波多尺度分析的重力反演在异常体重力异常信号提取、重力异常垂向分辨率和抗噪性方面均具有较好优势。鉴于此，本项目给出反演断层参数的重力异常多尺度边缘方法，通过推导建立断层参数与重力异常多尺度边缘之间非线性关系，判定断层位置与类型，反演断层密度与几何参数，并将其应用于反演深圳地区主干断层参数。研究成果不仅可以应用于断层的研究，同时也为相关地球物理反演提供新途径。

准确、高效确定城市断层的参数对城市的合理规划建设、长期的地质灾害防治、社会的可持续发展等具有重要意义。本项目提出了确定城市断层参数的重力异常多尺度边缘反演新方法，该方法相对于传统地震勘探、电发勘探、地质雷达等方法具有成本低、效率高等优势。主要研究成果包括：（1）通过理论模型确定了重力异常多尺度分析的最优小波基为Dmey小波；（2）密度误差在2%以内时，断层上盘上底面、上盘下底面、下盘上底面、下盘下底面和倾角的误差分别在0.5%、0.4%、0.4%、0.3%和5%以内；（3）通过理论模型模拟分析验证了本项目提出算法的正确性；（4）确定了深圳市主干断层的位置、参数，与相关结果能够很好吻合，进一步验证了本文计算方法的有效性；（5）完成了一套系统的研究城市断层的重力异常多尺度边缘反演理论，并研制了相应软件平台。项目研究成果既为相关城市断层探测提供了新途径，也为其他地球物理反演提供了参考方案。