Development and Testing of a Shielded Ocean-Bottom Seismometer to Reduce Seafloor Low-Frequency Noise

降低海底低频噪声的屏蔽海底地震仪的开发和测试

• 批准号: 0825077
• 负责人: Spahr Webb
• 金额: $ 19.53万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0825077&HistoricalAwards=false
• 关键词: Development; Testing; Shielded; Ocean; Bottom

The PI?s request funding to develop and test a shielded ocean bottom seismometer (SOBS) as a strategy for reducing the effect of current-generated tilt noise on low-frequency seismic observations made at the seafloor. The sensitive seismic sensor will be placed within a large circular steel shield that also serves as the instrument?s anchor. It is expected that this shield will reduce the current flow near the sensor reducing noise levels greatly. The establishment of fleets of large numbers of ocean bottom seismometers (OBS) capable of recording for more than a year has made it possible to study Earth structure beneath the oceans using seismic observations in much greater resolution than previously possible. The low frequency performance of these sensors is however poor compared to land sites because of very high noise levels caused by ocean currents. These high levels makes current OBS observations nearly useless for observations of Love waves, shear splitting, and receiver function analysis and can prevent the detection of shear wave arrivals from even large earthquakes at the noisier sites. Broader Impacts: One reviewer said that a better method for recording horizontal seismic energy (e.g. love waves) will benefit the entire marine (and land) geophysical community. In this regard current OBS observations are semi-limited in their ability to image Earth structure because this shear-wave data is not easily resolved. Any solution to enhance these recordings is a step toward better data resolution and interpretation.

皮？S要求提供资金，以开发和测试屏蔽海底地震仪(SOBS)，以此作为减少洋流产生的倾斜噪声对海底低频地震观测的影响的战略。灵敏的地震传感器将被放置在一个巨大的圆形钢盾构内，该盾构也用作仪器-S锚。预计这个屏蔽会减少传感器附近的电流，大大降低噪音水平。大量能够记录一年以上的海底地震仪的建立使利用比以前可能的分辨率高得多的地震观测来研究海洋下的地球结构成为可能。然而，与陆地站点相比，这些传感器的低频性能较差，因为洋流造成的噪音水平非常高。这些高水平使得目前的OBS观测对于Love波的观测、剪切分裂和接收器函数分析几乎毫无用处，并可以阻止在噪音较大的地点检测到即使是大地震的横波到达。更广泛的影响：一位评价者说，记录水平地震能量(例如洛夫波)的更好方法将使整个海洋(和陆地)地球物理界受益。在这方面，目前的OBS观测成像地球结构的能力是半受限的，因为这种横波数据不容易分辨。任何增强这些记录的解决方案都是朝着更好的数据分辨率和解释迈出的一步。