Finite‐difference P wave travel time seismic tomography of the crust and uppermost mantle in the Italian region
Finite‐difference P wave travel time seismic tomography of the crust and uppermost mantle in the Italian region
复制标题
意大利地区地壳和上地幔的有限差分纵波走时地震层析成像
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
Andrea Morelli
中科院分区：
文献类型：
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作者：
L. Gualtieri;Paola Serretti;Andrea Morelli
我们提出了意大利地区地壳和最浅地幔的3-D P波速度模型，其中包括通过区域地震走时层析成像获得的修订后的莫霍面深度图。我们从1988年至2007年发生在该地区的6850次地震中反演了191，850个Pn和Pg波到达时间，这些地震由264个永久地震台站记录。我们采用高分辨率线性B样条模型表示，水平网格间距为0.1°，垂直网格间距为2 km，采用精确的有限差分正演计算方案。我们的非线性迭代反演过程使用最近的欧洲参考三维地壳模型EP crust作为先验信息。我们得到的模型显示，地壳中有两个速度相对较低的弧线，沿着阿尔卑斯山和亚平宁山脉，位于板块之间的碰撞带之下。在西阿尔卑斯山下，我们检测到Ivrea体的存在，由强烈的高P波速度异常表示。我们还映射的莫霍面不连续的反演，成像为地壳和地幔之间的相对尖锐的过渡，其中P波速度步骤的值大于8公里/秒。这个简单的条件产生的图像与以前的研究，使用显式表示的不连续性相当一致。我们发现一个复杂的岩石圈结构，其特点是浅莫霍面靠近第勒尼安海，中间深度沿着亚得里亚海海岸，和最深的莫霍面下的两个山带。
We present a 3‐D P wave velocity model of the crust and shallowest mantle under the Italian region, that includes a revised Moho depth map, obtained by regional seismic travel time tomography. We invert 191,850 Pn and Pg wave arrival times from 6850 earthquakes that occurred within the region from 1988 to 2007, recorded by 264 permanent seismic stations. We adopt a high‐resolution linear B‐spline model representation, with 0.1° horizontal and 2 km vertical grid spacing, and an accurate finite‐difference forward calculation scheme. Our nonlinear iterative inversion process uses the recent European reference 3‐D crustal model EPcrust as a priori information. Our resulting model shows two arcs of relatively low velocity in the crust running along both the Alps and the Apennines, underlying the collision belts between plates. Beneath the Western Alps we detect the presence of the Ivrea body, denoted by a strong high P wave velocity anomaly. We also map the Moho discontinuity resulting from the inversion, imaged as the relatively sharp transition between crust and mantle, where P wave velocity steps up to values larger than 8 km/s. This simple condition yields an image quite in agreement with previous studies that use explicit representations for the discontinuity. We find a complex lithospheric structure characterized by shallower Moho close by the Tyrrhenian Sea, intermediate depth along the Adriatic coast, and deepest Moho under the two mountain belts.