川滇地区陆地流动重力测网场源分辨能力评估

陆地重力测量是研究地球内部物质运移和质量变化的重要手段, 场源分辨能力是评估流动重力测网监测效能和由场及源应用研究的关键指标。 本文以构造运动和地震活动活跃的川滇地区为例, 在设定场源异常体参数下, 通过Tesseroid网格模型建立不同分辨率的重力异常扰动模型检测板, 并基于川滇地区陆地流动重力测网测点分布, 对比反距离加权法、 Krigng插值法和最小二乘配置法对模型异常检测场的恢复效果。 在此基础上, 基于不同分辨率的模型检测板和模型抗噪分析结果, 研究川滇地区陆地流动重力测网的空间分辨率和场源反演分辨能力, 进而评估该地区重力测网的场源分辨能力, 并对该地区2014至2017年测网实测数据开展应用研究。 结果表明, 最小二乘配置法对川滇地区重力场恢复效果最佳, 川滇地区陆地流动重力测网大部分地区的空间分辨率优于0.75°×0.75°, 部分地区可达0.25°×0.25°; 在Ⅰ级活动地块边界带为0.50°×0.50°, 在Ⅱ级活动地块边界带优于0.75°×0.75°; 进一步根据活动地块边界和重力测点分布, 对川滇地区分区开展陆地流动测网场源分辨能力评估。

Evaluation of Field Source Resolution of Terrestrial Mobile Gravity Network in Sichuan-Yunnan Region

Terrestrial gravity measurement is an important means of studying the interior material movement and mass changes in the crust, and the field source resolution is a key indicator to assess the monitoring efficiency of the mobile gravity network. In this paper, we studied the gravity network of Sichuan-Yunnan region, where the tectonic movement and seismicity is active. Based on the field source anomaly parameters and the distribution of measuring points of the network, we calculated the checkboard of gravity anomaly by Tesseroid model, and comparison of model anomalies recovered by Inverse-distance-weighting method, Kriging method and Least-square-collocation-method, respectively. On this basis, we evaluated the capacity of the field source resolution of the gravity network in Sichuan-Yunnan region, and obtained the gravity changes from 2014 to 2017 in the region. The results show that the Least-square-collocation-method is the optimal method to recover the gravity field in the Sichuan-Yunnan region. The spatial resolution of land-based mobile gravity network is better than 0.75°×0.75° in most of the Sichuan-Yunnan region, and in some area even to 0.25°×0.25°. The spatial resolution is 0.50°×0.50°in the first-order active block boundary zone, and that is better than 0.75°×0.75° in the second-order active block boundary zone. Lastly according to active block boundaries and gravity measurement points, we evaluated the capacity of the field source resolution of the land-based mobile gravity network in different zones in Sichuan-Yunnan region.