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首页> 外文学位 >The development of a deep-towed gravity meter, and its use in marine geophysical surveys of offshore southern California and an airborne laser altimeter survey of Long Valley, California.
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The development of a deep-towed gravity meter, and its use in marine geophysical surveys of offshore southern California and an airborne laser altimeter survey of Long Valley, California.

机译：拖曳式重力仪的开发，及其在加利福尼亚南部近海的海洋地球物理勘测和加利福尼亚州长谷的机载激光高度计勘测中的使用。

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摘要

Marine Gravity is presently measured on the sea surface and on the sea floor. Surface measurements suffer from a loss of resolution, and seafloor measurements are slow to perform. The TOWDOG was created to operate near the seafloor but have a faster data recovery rate than seafloor measurements. It is a Lacoste and Romberg gravity meter, mounted inside a pressure case, and placed upon a platform which is stable while being towed. The instrument's depth is determined by pressure measurements. Its horizontal position is calculated using a dynamic model of the towing cable.;The first deployment of the instrument was in the San Diego Trough, a sedimentary basin offshore San Diego. Multiple gravity tracks were obtained at a depth of 935 meters. The rms repeatability between coincident tracks is 0.4 mGal. The inter-track gravity signal is coherent for wavelengths greater than 640 meters. A 1-km-wide seafloor depression in the Trough generates a 0.7 mGal gravity anomaly, which is seen in the data when 3 tracks are stacked.;The goal of the San Diego Trough survey was to determine if a significant density contrast exists across the basin's central axial fault. The survey reveals that no discernible contrast exists across the near-surface part of the fault. Two-dimensional gravity modeling constrained by seismic reflection profiles yields a depth to basement of 3.8 to 4.8 km below sea-level. A 3-component model (younger sediment, older, sedimentary rocks, and acoustic basement), best fits the seismic and gravity data.;The laser altimeter survey of Long Valley, California tests the capabilities of an aircraft-mounted laser in monitoring time-varying uplift of a resurgent volcanic dome. The system can profile a lake surface with an r.m.s. repeatability of 3-5 cm, and can detect time-varying height changes of the lake level of 5 cm per day. This should be sufficiently accurate to detect yearly uplift of 4 cm per year, as is occurring at Long Valley. The detection of such signals has not yet been proven, but the error level of the data is sufficiently low to provide encouragement that such a goal will eventually be attained.
机译：目前在海面和海底测量海洋重力。表面测量遭受分辨率损失，并且海底测量执行缓慢。 TOWDOG的创建目的是在海底附近操作，但其数据恢复速率比海底测量更快。它是Lacoste和Romberg重力仪，安装在压力箱内，并放置在拖曳时稳定的平台上。仪器的深度取决于压力测量值。它的水平位置是使用拖缆的动态模型来计算的。仪器的首次部署是在圣地亚哥海槽（圣地亚哥海域的一个沉积盆地）中进行的。在935米的深度获得了多个重力轨道。重合磁道之间的均方根重复性为0.4 mGal。轨道间重力信号对于大于640米的波长是相干的。槽中1公里宽的海底凹陷会产生0.7 mGal的重力异常，这在3条轨道叠置时在数据中可以看到。圣地亚哥槽调查的目的是确定整个海床是否存在显着的密度对比。盆地的中央轴向断裂。调查显示，断层近地表部分没有明显的对比。受地震反射剖面约束的二维重力模型产生的地下深度为海平面以下3.8至4.8 km。 3分量模型（较新的沉积物，较旧的沉积岩，沉积岩和声学基底）最适合地震和重力数据。加利福尼亚州长谷的激光高度计调查测试了机载激光器在监视时间方面的能力，火山圆顶的隆起变化。该系统可以通过r.m.s对湖面进行轮廓分析3-5厘米的重复性，并且可以检测到每天5厘米的湖面高度随时间变化。这应该足够准确，以检测到长谷地区每年发生的4 cm的年度隆起。对这种信号的检测尚未得到证实，但是数据的错误级别足够低，无法鼓励人们最终实现这一目标。

著录项

  • 作者

    Ridgway, Jeffrey R.;

  • 作者单位

    University of California, San Diego.;

  • 授予单位 University of California, San Diego.;
  • 学科 Geotechnology.;Electrical engineering.;Remote sensing.
  • 学位 Ph.D.
  • 年度 1997
  • 页码 231 p.
  • 总页数 231
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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