Abstract. The investigated area of the NW Dinarides is located at the NE corner of the Adriatic microplate and is bordered by the Adriatic foreland, the Southern Alps, and the Pannonian basin. Its complex crustal structure is the result of interactions among different tectonic units, mainly the Eurasian plate and the Adriatic microplate. Despite numerous seismic studies in this tectonically complex area, there is still a need for a detailed, small scale study focusing mainly on the upper, brittle part of the crust. We investigated the crustal velocity structure with 1-D simultaneous hypocenter-velocity inversion using routinely picked P wave arrival times. Most of the computed models converged to a stable solution in the depth range between 0 and 26 km. We further evaluated the inversion results with hypocenter shift tests, high and low velocity tests, and relocations. This helped us to select two best performing velocity models for the whole study area. Based on these results and the seismicity distribution, we further divided the study area into three parts, redefined the earthquake-station geometry, and performed inversion for each part separately to gain better insight into the crustal structure of each subregion. Median velocities in the upper 20 km of the crust in the eastern subregion are lower compared to the regional median and the median of the other two subregions. The northwestern and southwestern subregions are very similar in terms of crustal structure between about 8 and 23 km depth. The largest difference between them is observed in the upper 8 km, with higher median velocities in the southwestern subregion. Compared to the model currently used at Slovenian Environment Agency to locate earthquakes, the velocity models obtained show higher velocities in the upper 30 km depth and agree very well with some of the previous studies. In addition to general structural implications and a potential for improving seismic tomography results, the new 1-D velocity models can also be used for fast routine earthquake location and for detecting systematic travel time errors in seismological bulletins.

中文翻译：

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NW Dinarides 地壳的一维速度结构建模

摘要。NW Dinarides 研究区位于亚得里亚海微板块的东北角，与亚得里亚海前陆、南阿尔卑斯山和潘诺尼亚盆地接壤。其复杂的地壳结构是不同构造单元相互作用的结果，主要是欧亚板块和亚得里亚海微板块。尽管在这个构造复杂的地区进行了大量的地震研究，但仍然需要进行详细的小规模研究，主要关注地壳上部的脆性部分。我们使用常规选择的 P 波到达时间，通过一维同步震源速度反演研究了地壳速度结构。大多数计算模型在 0 到 26 公里的深度范围内收敛到一个稳定的解。我们通过震源偏移测试、高速和低速测试进一步评估了反演结果，和搬迁。这有助于我们为整个研究区域选择两个性能最佳的速度模型。根据这些结果和地震活动分布，我们将研究区进一步划分为三个部分，重新​​定义了地震台站几何形状，并分别对每个部分进行了反演，以更好地了解每个子区域的地壳结构。东部次区域地壳上部 20 公里的中值速度低于区域中值和其他两个次区域的中值。西北亚区和西南亚区在深度约 8 至 23 公里之间的地壳结构方面非常相似。它们之间的最大差异出现在上部 8 公里处，西南次区域的中值速度较高。与斯洛文尼亚环境署目前用于定位地震的模型相比，所获得的速度模型在上层 30 公里深度显示出更高的速度，并且与之前的一些研究非常吻合。除了一般的结构意义和改进地震层析成像结果的潜力外，新的一维速度模型还可用于快速常规地震定位和检测地震公报中的系统走时误差。