Resolving Earth's Free Oscillation Spectrum: New Data and New Techniques

解析地球的自由振荡频谱：新数据和新技术

• 批准号: 9508113
• 负责人: Freeman Gilbert
• 金额: $ 9万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-05-15 至 1998-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9508113&HistoricalAwards=false
• 关键词: Resolving; Earth; Free; Oscillation; Spectrum

9508113 GILBERT This research involves the complete re-evaluation of the Earth's complete normal-mode spectrum in light of recent large earthquakes. It is fair to say that, before the June 9, 1994, great deep Bolivian earthquake, observational free-oscillation seismology had gone into a state of suspended animation. A lack of very large events and, in particular, the lack of very large deep events made progress difficult and incremental. The Fiji event in March rekindled some interest since it was the largest deep event to be digitally recorded since the 1970 Columbian event, but it was rapidly eclipsed by the Bolivian event. Not only was the Bolivian event bigger than the 1970 Columbian event but it was recorded by an unprecedented number of observatory-quality digital stations. For those who know what is possible with hand-digitized recordings of the Columbian event, the new data promise a quantum improvement in our knowledge of the seismic response of the Earth at long-periods. It is anticipated that this research will lead to, at the minimum: stringent constraints on anisotropy in the core, constraints on the relative P and S velocity variations in the mantle, constraints on 3-D attenuation structure (at least of even harmonic degree), high resolution 1-D models with resolution lengths below 100 km for precisians of 0.1%, and an accurate description of the seismic spectrum at long periods making better determination of long-period source behavior for large events possible. *** ??

9508113吉尔伯特这项研究涉及到根据最近的大地震对地球完整的正常模谱进行彻底的重新评估。可以说，在1994年6月9日玻利维亚深大地震之前，观测自由振荡地震学已经进入了休眠状态。缺少大型活动，特别是缺少大型深度活动，使取得进展变得困难和渐进。3月份的斐济事件重新引起了人们的兴趣，因为它是自1970年哥伦比亚事件以来最大的有数字记录的深部事件，但它很快就被玻利维亚事件黯然失色。玻利维亚的事件不仅比1970年的哥伦比亚事件更大，而且它被空前数量的天文台质量的数字站记录下来。对于那些知道用手持数字化记录哥伦比亚事件的人来说，这些新数据有望极大地提高我们对地球长周期地震响应的了解。预计这项研究至少将导致：对核心各向异性的严格约束，对地幔相对P和S速度变化的约束，对三维衰减结构的约束(至少是偶次谐度)，分辨率长度低于100公里的高分辨率一维模型(精度为0.1%)，以及对长周期地震谱的准确描述，使更好地确定大事件的长周期震源行为成为可能。*？？