Long‐term tilt and acceleration data from the Logatchev Hydrothermal Vent Field, Mid‐Atlantic Ridge, measured by the Bremen Ocean Bottom Tiltmeter
Long‐term tilt and acceleration data from the Logatchev Hydrothermal Vent Field, Mid‐Atlantic Ridge, measured by the Bremen Ocean Bottom Tiltmeter
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DOI：
10.1029/2007gc001917
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发表时间：
2008-07
期刊：
影响因子：
3.7
通讯作者：
M. Fabian;H. Villinger
中科院分区：
文献类型：
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作者：
M. Fabian;H. Villinger
大西洋中脊洛加切夫热液喷口场（LHF）的长期海底变形在很大程度上未被探索和未知，尽管LHF多年来一直是国际研究的焦点。由于海底倾斜和垂直加速度提供了有关海底变形的关键信息，2005年5月在LHF的14°45′11.7″N，44°58′47.0″W，3035 m水深的位置部署了不莱梅海底倾斜仪（OBT）。OBT记录了384天，并于2007年1月恢复。强烈的倾斜步骤和强烈的倾斜变化在不到一分钟到几天的时间内，在大约10 mrad的范围内，主要与地形对齐，可能表明附近的质量运动，如由于局部隆起或沉降造成的大块物质雪崩，或者可能显示构造活动。传感器封装中的Servo K‐Beam型垂直对齐高分辨率微机电系统（MEMS）加速度计似乎有助于区分由真实旋转引起的倾斜信号和与OBT在水平方向上的瞬时平移运动相关的假倾斜。速矢图显示椭圆形的运动模式，约1毫拉德的总倾斜幅度和不同的方向倾斜向热液喷口。至于后者的信号是否与热液流体循环有关，则有待推测。这些倾斜信号和加速度的幅度谱显示离散线大多在0.1和50兆赫之间。频谱显示了这些信号的周期性特征，并且还证明了已知显示较低信号频率的潮汐或底流或通常具有较高频率的震颤很可能不是原因。与陆上和海上的研究相比，LHF最有可能是一个强烈和高度可变的海底变形区。
Long‐term seafloor deformations in the Logatchev Hydrothermal Vent Field (LHF) at the Mid‐Atlantic Ridge are largely unexplored and unknown, even though the LHF has been the focus of international research for many years. As seafloor tilt and vertical acceleration provide key information about seafloor deformations, the Bremen Ocean Bottom Tiltmeter (OBT) was deployed in May 2005 at position 14°45′11.7″N, 44°58′47.0″W, 3035 m water depth in the LHF. The OBT recorded 384 days and was recovered in January 2007. Strong tilt steps and strong gradual tilt changes over less than a minute to days in the range of some 10 mrad and aligned mostly with the topography possibly indicate nearby mass movements like avalanches of bulk material due to local uplift or subsidence or may show tectonic activity. A vertically aligned high‐resolution microelectromechanical systems (MEMS) accelerometer of type Servo K‐Beam in the sensor package seems to be helpful to distinguish between tilt signals caused by a true rotation and fake tilt related to a transient translational motion of the OBT in a horizontal direction. Hodographs show elliptic motion patterns with about 1 mrad total tilt amplitude and distinct orientations of tilt toward hydrothermal vents. It is up to speculation whether the latter signals are related to hydrothermal fluid circulation. The amplitude spectra of these tilt signals and acceleration show discrete lines mostly between 0.1 and 50 mHz. The spectra show the periodic character of those signals and also proof that tides or bottom currents, which are known to show lower signal frequencies, or tremor, which generally has higher frequencies, are most likely not the reason. Compared with studies onshore and offshore, the LHF is most likely an area of strong and highly variable seafloor deformations.