Evidence of large scale deformation patterns from GPS data in the Italian subduction boundary
Evidence of large scale deformation patterns from GPS data in the Italian subduction boundary
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DOI：
10.1016/j.epsl.2011.09.034
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发表时间：
2011-11-15
影响因子：
5.3
通讯作者：
Riguzzi, Federica
中科院分区：
文献类型：
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作者：
Devoti, Roberto;Esposito, Alessandra;Riguzzi, Federica
我们提出的速度场在意大利来自300多个连续的GPS站在1998-2009年的时间跨度。全球定位系统网络绘制了全国地图，站点间平均距离约为50公里，为研究地中海中部正在发生的变形过程提供了宝贵的数据来源。估计的水平和垂直速度场显示主要的显着特征，也不太为人所知的二阶运动学特征。沿着地形脊的整个亚平宁山脉和阿尔卑斯山脉带总体上呈隆起的特征，而波河平原则显示出自西向东逐渐增加的沉降。亚平宁山脉带表现出明显的伸展（50-80 × 10（-9）yr（-1）），而北方西西里岛、阿尔卑斯山脉东部和北方亚平宁山脉东北前缘则表现出挤压构造体制（25-50 × 10（-9）yr（-1））。在亚平宁山脉中部和南部的增生棱柱体上探测到了大尺度波长（类似于100 km）的二级变形图案，这些图案与其他地球物理数据（Vp异常、地震各向异性等）高度相关。并与深根段（70-100 km）有关，以不同的俯冲体制为标志。显然，在这个尺度上，观测到的变形是由整个岩石圈控制的。我们解释这些变形作为不同的俯冲机制的结果，如俯冲回滚速度的变化影响俯冲带的不同部分和/或地幔流附近的板边缘。再往南，在中部-南部西西里，我们检测到（-1.1 +/- 0.2）毫米/年的收缩，可能容纳部分非洲-欧亚大陆的收敛在外部冲断锋的亚平宁-马格里布带。这一假设与一项独立的分析相一致，该分析认为西西里基底冲断带仍然活跃。新GPS速度场的ITRF 2005估计也以SINEX格式作为补充文件S1提供。(C)2011 Elsevier B. V.保留所有权利。
We present the velocity field in Italy derived from over 300 continuous GPS stations operated in the 1998-2009 time span. The GPS network maps the whole country with a mean inter-site distance of about 50 km and provides a valuable source of data to study the ongoing deformation processes in the central Mediterranean. The estimated horizontal and vertical velocity fields show major significant features and also less known second-order kinematic features. A general uplift characterizes the whole Apennines and Alpine belts that follow the topographic ridge, whereas the Po Plain shows a gradually increasing subsidence from west to east. The Apennines belt displays a distinctive extension (50-80 10(-9) yr(-1)) while compressive tectonic regimes characterize northern Sicily, eastern Alps and the northeast front of the northern Apennines (25-50 10(-9) yr(-1)). Second-order deformation patterns, on large scale wavelength (similar to 100 km) have been detected on the accretionary prism of central and southern Apennines that are highly correlated with other geophysical data (Vp anomalies, seismic anisotropy, etc.) and related to deep rooted sections (70-100 km), marked by different subduction regimes. Apparently at this scale-length the observed deformations are governed by the lithosphere as a whole. We interpret these deformations as a result of different subduction mechanisms, such as variations of the subduction rollback velocity affecting different segments of the subduction zone and/or to mantle flows in proximity of the slab edges. Further south, in central-southern Sicily, we detect a contraction of (-1.1 +/- 0.2) mm/yr that probably accommodates part of the Africa-Eurasia convergence on the outer thrust front of the Apennines-Maghrebides belt. This hypothesis agrees with an independent analysis of the seismicity associated to the Sicilian Basal Thrust thought to be still active. The ITRF2005 estimates of the new GPS velocity field are available also in SINEX format as supplementary file S1. (C) 2011 Elsevier B.V. All rights reserved.