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Topographically Predicted Vertical Gravity Gradient Field and Its Applicability in 3D and 4D Microgravimetry: Etna (Italy) Case Study
Pure and Applied Geophysics ( IF 1.9 ) Pub Date : 2020-02-05 , DOI: 10.1007/s00024-020-02435-x
Peter Vajda , Pavol Zahorec , Juraj Papčo , Daniele Carbone , Filippo Greco , Massimo Cantarero

Some geophysical or geodynamic applications require the use of true vertical gradient of gravity (VGG). This demand may be associated with reductions of or corrections to observed gravity or its spatiotemporal changes. In the absence of in situ measured VGG values, the constant value of the theoretical (normal) free air gradient (FAG) is commonly used. We propose an alternative to this practice which may significantly reduce systematic errors associated with the use of constant FAG. The true VGG appears to be better approximated, in areas with prominent and rugged topography, such as alpine or some volcanic regions, by a value based on the modelled contribution of the topographic masses to the gradient. Such prediction can be carried out with a digital elevation model (DEM) of sufficient resolution and accuracy. Here we present the VGG field computed for Mt. Etna (Italy), one of the most active and best monitored volcanoes worldwide, to illustrate how strongly the VGG deviates spatially from constant FAG. The predicted (modelled) VGG field is verified by in situ observations. We also take a look at the sensitivity of the VGG prediction to the resolution and quality of used DEMs. We conclude with discussing the applicability of the topo-predicted VGG field in near surface structural and volcanological micro-gravimetric studies.

中文翻译:

地形预测的垂直重力梯度场及其在 3D 和 4D 微重力测量中的适用性:埃特纳火山(意大利)案例研究

一些地球物理或地球动力学应用需要使用真正的垂直重力梯度 (VGG)。这种需求可能与观测到的重力或其时空变化的减少或修正有关。在没有原位测量的 VGG 值的情况下,通常使用理论(正常)自由空气梯度 (FAG) 的常数值。我们提出了一种替代这种做法的方法,它可以显着减少与使用恒定 FAG 相关的系统误差。在具有突出和崎岖地形的地区,例如高山或一些火山地区,真实的 VGG 似乎可以更好地近似于基于地形质量对梯度的建模贡献的值。可以使用具有足够分辨率和准确度的数字高程模型 (DEM) 来执行此类预测。在这里,我们展示了为 Mt 计算的 VGG 场。埃特纳火山(意大利)是世界上最活跃和监测最好的火山之一,用于说明 VGG 在空间上偏离恒定 FAG 的程度。预测(建模)VGG 场通过原位观测得到验证。我们还研究了 VGG 预测对使用的 DEM 的分辨率和质量的敏感性。我们最后讨论了地形预测 VGG 场在近地表结构和火山学微重力研究中的适用性。我们还研究了 VGG 预测对使用的 DEM 的分辨率和质量的敏感性。我们最后讨论了地形预测 VGG 场在近地表结构和火山学微重力研究中的适用性。我们还研究了 VGG 预测对使用的 DEM 的分辨率和质量的敏感性。我们最后讨论了地形预测 VGG 场在近地表结构和火山学微重力研究中的适用性。
更新日期:2020-02-05
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